Phase check in beta_from_phase() in GetLLM added
Crash occured in beta_from_phase() when the phases have not been
calculated for the AC case when BPMs next to AC dipole were missing.
Phase dictionary is now checked at the beginning of this function,
and if not available will stop and return empty variables.
Merge branch 'master' of https://github.com/pylhc/Beta-Beat.src