Add test suite events to indicate when a feature is detected or not

These are needed by the bridge test suite tests for them to be able to run
against Asterisk 11.

Review: https://reviewboard.asterisk.org/r/2751/



git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/11@396884 f38db490-d61c-443f-a65b-d21fe96a405b