Add preceding context of unit to email.

        Fixes #3.
Comment interval in config, and make it match default value
Pick input interval over config interval
Rename variables and remove unneeded pragma
Renamed 'interval' to 'context_interval'.
Merge remote-tracking branch 'origin/master' into jkarni/issues/3

Conflicts:
	src/Process.hs
Merge pull request #15 from zalora/jkarni/issues/3

Add preceding context of unit to email.