Properly inset cell separator

When a cell contains content that is a reply to content in
another cell, inset cell separator below the current cell
to the left.
Fix appearance of Like/Unlike button

Also decouple LFSDetailView from model specifics (number of likes etc).
clean up code in LFSDetailViewController
Opines now working

Some edge cases remain (such as the fact that only one collection is supported
because of hardcoded user id).
Merge pull request #46 from Livefyre/dev

Add opine functionality, reflect content hierarchy through cell separators