[mythtv-cmyth] Deleting timer vs Deleting live recording

Reuse IsMyLIveTVRecording() as possible to check handle recording is the live.
Never delete live recording. If it is kept then ignore it now else reject action.
[mythtv-cmyth] Switch channel: CheckChannel() is not expected service

Use IsTunable() instead.
Merge pull request #3 from janbar/keep_live_rec_4

Fix after Keep live rec 4