Fix memory leak while loading priority modules and adding formats

This patch fixes two memory leaks:
 * When we load a module with the LOAD_PRIORITY flag, we remove its entry from
   the load order list. Unfortunately, we don't free the memory associated with
   entry in the list. This patch corrects that and properly frees the memory
   for the module in the list.

 * When adding a custom format (such as SILK or CELT), the routine for adding
   the format was leaking a reference. RAII_VAR cleans this up properly.

........

Merged revisions 391489 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/11@391507 f38db490-d61c-443f-a65b-d21fe96a405b