Issue #7 Git commit hash can now be entered as a environment variable

Per my Issue #7 this is how I fixed it and this is running on our Jenkins server.
In essence it's an easy change, just adding a check of the environment variables.

1. Check the environment variables for GIT_COMMIT
2. Fallback to Git Plugin to retrieve commit hash

Ps: Intellij reformatted the code resulting in a lot more changes than required.