Added bookmarks

• Added:
- bookmarks for GabPRO members only
- migration for creation of StatusBookmarks
- all necessary routes, controllers
- redux for adding, removing, fetching and displaying bookmarks
- bookmark icon
- doorkeeper scopes
- backend and frontend support

Bookmarks behave like likes/favorites, except they aren't shared with other users and do not have an associated counter.

https://github.com/tootsuite/mastodon/commit/dfea7368c934f600bd0b6b93b4a6c008a4e265b0

config/initializers/doorkeeper.rb

@@ -58,6 +58,7 @@ Doorkeeper.configure do
   optional_scopes :write,
                   :'write:accounts',
                   :'write:blocks',
+                  :'write:bookmarks',
                   :'write:conversations',
                   :'write:favourites',
                   :'write:filters',
@@ -71,6 +72,7 @@ Doorkeeper.configure do
                   :read,
                   :'read:accounts',
                   :'read:blocks',
+                  :'read:bookmarks',
                   :'read:favourites',
                   :'read:filters',
                   :'read:follows',