Added SwitchCaseFixer - first draft.

This is to fix #776.  Please refer to original PR - https://github.com/fabpot/PHP-CS-Fixer/pull/2 for a bit more details.
Try bottom-up approach.
Firstly fix the most nested structure, then fix outer structer, treating the inner one as complete block of code that don't need to be fixed (maybe only general level of indent if needed, such as add 4 spaces for all lines of inner structure).