Integrate comment moderation prototypes

Misc:
* Flag-related stuff is not yet implemented
* rename `comments_review` function as `comment_moderation` to match language used elsewhere
* utility function `detail_link` now supports linking to users and to `MapFeature` subclasses like `Plot`
* Fix initialization of photo review page
Merge pull request #1593 from RickMohr/integrate-comment-moderation

Integrate comment moderation prototypes
Lint removal
Add model and migration rules for TreeFavorite
Merge pull request #1595 from steventlamb/topic/add_tree_favoriting

Add model and migration rules for TreeFavorite
Add leaflet-draw 0.2.2 plugin.

This is for drawing the polygon feature for modeling tree distributions.
Merge pull request #1600 from kdeloach/topic/leaflet-draw

Add leaflet-draw 0.2.2 plugin.