Quick Create: Use the proper post type label for the button

See #59
Quick Create: Show an error if trying to create a post where the post type isn't viewable on calendar

See #59
Quick Create: Better i18n

See #158
Quick Create: Better docs and method name

See #59
A follow link for Manage Posts, Calendar, and Story Budget

This adds a "Follow" link to post row actions to Manage Posts, Calendar, and Story budget views. It also removes the unfollowing_users taxonomy, as that hasn't ever been used, and refactors follow_post_users and unfollow_post_users(), as the latter hasn't ever worked.

Lastly, it refactors the row actions for the Story Budget so it's easy to hook on this follow link

See #130
Linked features from dashboard
Proper use of sprintf, and consolidate some code
Props for #185
A different way of binding events, which means the event is dynamically bound instead of static.
Merge pull request #185 from Automattic/follow-link

A follow link for Manage Posts, Calendar, and Story Budget
Update readme for #185
Enable editing of metadata on calendar.

Fix how overlay displays.

Add datetime picker functionality.

Fixing some spacing issues.

Added spinners to make things look nice when ajax is required.

Chose a different dom element to bind to that doesn't get erased.

Investigating CSS rendering of single_li elements.

Finalized removal of ajax when subsituting for select elements.

Finalizing inserting selet lists without ajax.

Fix issues with "user" dropdown.