Use copy accessors for classes where mutable equivalent exists

copy method is identity for immutable objects but will return a new
immutable object if passed NSMutable* reference.
Use float notation to prevent inline casts

Also add some comments
Partly working commit
another partial commit
Refactor

The goal is to make view interfaces more abstract
(content-independent). Also remove some dead code
Basic support for UIAppearance

Can set background color of LFSAttributedTextCell in didFinishLaunching...
Full support for UIAppearance in LFSAttributedTextCell

Support setting custom font sizes and colors app-wide in didFinishLaunching...

This commit also restores right accessory view (date).
Merge pull request #24 from Livefyre/dev

Support UIAppearance protocol for easy customization of fonts and colors