Changed themes to be a NSDictionary object.
Added the singleton usage.
Fixed a bug in theme loader.
Refactored theme to match the coding convention.
Made edgeInsetsForKey could be set by using string (top, left, bottom, right).
Made pointForKey, could be set by  using string (x, y).
Made sizeForkey could be set by using string (width, height).
Added the documentation.
Merge branch 'feature/Refactor' into develop
Merge branch 'release/0.0.1'