Edit blogs, and add blog icons and banners (#460)

Also adds a parameter to `md_to_html` to only render inline elements (so that we don't have titles or images in blog descriptions). And moves the delete button for the blog on the edition page.

I still have to update the SQLite migration once others PRs with migrations will be merged.

Also, there will be a problem when you edit a blog while not owning its banner or icon: when validating they will be reset to their default values… I don't see a good solution to this until we have a better way to handle uploads with Rocket (the same is probably happening for articles btw).

And the icon/banner are not federated yet, I don't know if I should add it to this PR or if it can come after?

![image](https://user-images.githubusercontent.com/16254623/53894510-7d853300-4030-11e9-8a2c-f5c0b0c7f512.png)
![image](https://user-images.githubusercontent.com/16254623/53894539-8b3ab880-4030-11e9-8113-685a27be8d7c.png)

Fixes #453
Fixes #454

po/plume/ru.po

@@ -45,6 +45,18 @@ msgstr "Вы должны войти чтобы написать новый по
 msgid "You are not allowed to delete this blog."
 msgstr "Вы не автор этого блога."
 
+#, fuzzy
+msgid "You are not allowed to edit this blog."
+msgstr "Вы не автор этого блога."
+
+#, fuzzy
+msgid "You can't use this media as blog icon."
+msgstr "Вы не автор этого блога."
+
+#, fuzzy
+msgid "You can't use this media as blog banner."
+msgstr "Вы не автор этого блога."
+
 #, fuzzy
 msgid "You need to be logged in order to like a post"
 msgstr "Вы должны войти чтобы отмечать понравившиеся посты"
@@ -412,6 +424,13 @@ msgstr ""
 msgid "Read the detailed rules"
 msgstr "Прочитать подробные правила"
 
+msgid "None"
+msgstr "Нет"
+
+#, fuzzy
+msgid "No description"
+msgstr "Длинное описание"
+
 msgid "View all"
 msgstr "Показать все"
 
@@ -578,9 +597,6 @@ msgstr "Оставьте пустым если нет"
 msgid "Illustration"
 msgstr "Иллюстрация"
 
-msgid "None"
-msgstr "Нет"
-
 #, fuzzy
 msgid "This is a draft, don't publish it yet."
 msgstr "Этот пост ещё не опубликован."
@@ -707,34 +723,29 @@ msgstr ""
 "ней."
 
 #, fuzzy
-msgid "New Blog"
-msgstr "Новый блог"
+msgid "Edit \"{}\""
+msgstr "Редактировать"
 
-msgid "Create a blog"
-msgstr "Создать блог"
+msgid "Description"
+msgstr "Описание"
 
-msgid "Create blog"
-msgstr "Создать блог"
+msgid ""
+"You can upload images to your gallery, to use them as blog icons or banners."
+msgstr ""
 
 #, fuzzy
-msgid "There's one author on this blog: "
-msgid_plural "There are {0} authors on this blog: "
-msgstr[0] "Один автор в этом блоге: "
-msgstr[1] "{0} автора в этом блоге: "
-msgstr[2] "{0} авторов в этом блоге: "
+msgid "Upload images"
+msgstr "Загрузить"
+
+msgid "Blog icon"
+msgstr ""
+
+msgid "Blog banner"
+msgstr ""
 
 #, fuzzy
-msgid "There's one article on this blog"
-msgid_plural "There are {0} articles on this blog"
-msgstr[0] "Один пост в этом блоге"
-msgstr[1] "{0} поста в этом блоге"
-msgstr[2] "{0} постов в этом блоге"
-
-msgid "No posts to see here yet."
-msgstr "Здесь пока нет постов."
-
-msgid "New article"
-msgstr "Новая статья"
+msgid "Update blog"
+msgstr "Создать блог"
 
 #, fuzzy
 msgid "Be very careful, any action taken here can't be reversed."
@@ -745,6 +756,32 @@ msgstr ""
 msgid "Permanently delete this blog"
 msgstr "Удалить этот блог"
 
+#, fuzzy
+msgid "New Blog"
+msgstr "Новый блог"
+
+msgid "Create a blog"
+msgstr "Создать блог"
+
+msgid "Create blog"
+msgstr "Создать блог"
+
+msgid "{}'s icon"
+msgstr ""
+
+msgid "New article"
+msgstr "Новая статья"
+
+#, fuzzy
+msgid "There's one author on this blog: "
+msgid_plural "There are {0} authors on this blog: "
+msgstr[0] "Один автор в этом блоге: "
+msgstr[1] "{0} автора в этом блоге: "
+msgstr[2] "{0} авторов в этом блоге: "
+
+msgid "No posts to see here yet."
+msgstr "Здесь пока нет постов."
+
 #, fuzzy
 msgid "Articles tagged \"{0}\""
 msgstr "Статьи, отмеченные тегом «{0}»"
@@ -774,9 +811,6 @@ msgstr "Детали медиафайла"
 msgid "Media upload"
 msgstr "Загрузка медиафайлов"
 
-msgid "Description"
-msgstr "Описание"
-
 #, fuzzy
 msgid "Useful for visually impaired people, as well as licensing information"
 msgstr "Описание для лиц с нарушениями зрения и информация о лицензии"
@@ -808,6 +842,13 @@ msgstr ""
 msgid "Use as avatar"
 msgstr "Использовать как аватар"
 
+#, fuzzy
+#~ msgid "There's one article on this blog"
+#~ msgid_plural "There are {0} articles on this blog"
+#~ msgstr[0] "Один пост в этом блоге"
+#~ msgstr[1] "{0} поста в этом блоге"
+#~ msgstr[2] "{0} постов в этом блоге"
+
 #, fuzzy
 #~ msgid "{0}'s followers"
 #~ msgstr "Один подписчик"