Merge pull request #52 from danielhjames/2.5.x

SAAS-374 Don't expose API key when a component has failed
CC-5660: Unable to create shows with a rebroadcast

Two variables that are needed for the rebroadcast validation were deleted
before the 2.5.1 release. Just had to add them back in.
CC-5660: Unable to create shows with a rebroadcast

Used wrong formating for minutes
CC-5665: Timeout can occur when scheduling large playlists into linked shows

Added a temporary fix by extending the php time limit
CC-5666: Deleting a show instance can revert the 'no end' option
Added comments for a show_service function
Small Airtime Pro fix for ShowFormService
Updated install instructions for 2.5.x