Add CRON scheduling support

Add `--notify_early` option to schedule command

Add description content type

This is required to upload to PyPI.

Add support for concurrency levels.

Enhance concurrency support.

Add AzkabanPig option to include files.

This is for example useful for Python UDFs.

Add support for directly setting disabled jobs.

Also fix session ID bug.

better handling of pig jobs with project relative root

merge 2.0

version bump