Ruby: Correctly set access permissions for directory entries

Ruby: Correctly set access permissions for directory entries
The access permissions for the directory entries are not being set correctly.
This is because pointers are not used for handling directory entries.
function. get and set functions for access permissions have been added to the
Controller state machine. The changePermission() function provided by the
AbstractEntry and AbstractCacheEntry classes has been exposed to SLICC
code once again. The set_permission() functionality has been removed.

NOTE: Each protocol will have to define these get and set functions in order
to compile successfully.