This is now handled by the Heka formula the same way for all the Heka sandbox
decoders. https://github.com/tcpcloud/salt-formula-heka/pull/20

This filter should be configured by the heka formula itself.

The stacklight module dir is /usr/share/lma_collector/common, not
/usr/share/lma_collector_modules. This fixes it.

This fixes the decoder name in meta/heka.yml.

This commit removes the alarm-related filter configuration from meta/heka.yml.
Alarms will be defined in a different way (still under discussion).