Fix two issues that created crashes

1. The kSMInfoKeyPrivilegedExecutables key is not available in Yosemite, so I just use the string.
2. Added errors for cases where there were none and should have been.
Merge branch 'master' of github.com:lksoft/LKKit

* 'master' of github.com:lksoft/LKKit:
  Make sure that the calls to the XPC helper doesn't get stuck in a loop.
  Removed code that was deprecated as it was three to support 10.6, which Mail Plugin Manager No longer supports.