build and %post fixes

- enable back post-build-checks
- stop collectd before removing /var/lib/collectd/*
- correctly handle update/install (see https://fedoraproject.org/wiki/Packaging:ScriptletSnippets?rd=Packaging/ScriptletSnippets#Syntax)
fixed /var/lib/collectd/ cleanup
removed accidentaly submitted patch for network
always restart collectd (to make it simple)

added comments to make the current solution clean
Merge pull request #66 from webyast/status_postinstall_race_condition_fix

Status postinstall race condition fix