add FileCacheManager

Add support for caching information about state of fixing files.
Cache is supported only for phar version and version installed via composer.
 
 File will be processed by PHP CS Fixer only if any of the following conditions is fulfilled:
 * cache is not available,
 * fixer version changed,
 * file is new,
 * file changed.
When you have
/path/projectFoo
then you will have /path/projectFoo/.php_cs.cache file.

Then you may move whole project into:
/path/projects/foo (and file /path/projects/foo/.php_cs.cache)

With relative paths there will be no need to refix all files. With absolute paths there will be.