Add heka monitoring for validation stats.
Delete files if they *do* exist

Had the file-existence check inverted. Remove the negation.
Fix a few problems with heka 0.5
Merge branch 'master' of github.com:mozilla/telemetry-server
Merge branch 'master' into heka_0_5_update
Merge pull request #36 from mozilla/heka_0_5_update

Heka 0 5 update