Use /var/cache instead of /var/run as default folder for LogfileInput seek journals and
WhisperOutput db files, since /var/run is usually deleted on machine reboots.
Merge branch 'dev' into features/no-var-run

Conflicts:
	pipeline/filemonitor_test.go
	pipeline/logfile_input.go
	pipeline/whisper.go
Merge pull request #353 from mozilla-services/features/no-var-run

Use /var/cache instead of /var/run as default folder for LogfileInput se...