Title: fixed helpers failing to start and high cpu load when an unparsable local check is installed
Level: 1
Component: checks
Compatible: compat
Version: 1.2.8p5
Date: 1467278454
Class: fix

When python fails to parse a check file (local or shipped), the check_mk helpers would produce an
erro message and exit. check_mk would then restart the helper, repeating the process infinitely
which left check_mk in a non-working state, causing high cpu load and quickly growing the cmc.log.

This only occurs when installing syntactically broken checks so most users shouldn't be affected.
