Merge pull request #742 from mdaliejaz/add_message_based_task_plugin_api

Added message based task plugin api
#718 - Fix failing tests.
Merge pull request #746 from arvindsv/fix_build_task_plugin_json_api_change

#718 - Fix failing tests.
#718 - Fix acceptance test failing due to wrong merge.

There was a small mistake in 29e3b456e507eabfed856a3212cc16f5ee96da55, where it did not correctly
merge changes from 118794c4b73c6cca50004d01dbb9ea59a742837d. Acceptance tests failed because of
this.
Merge pull request #747 from arvindsv/fix_for_acceptance_test_wrong_merge

#718 - Fix acceptance test failing due to wrong merge.
#718 - Missed a test. Fix build.
Merge pull request #748 from arvindsv/fix_plugin_test

#718 - Missed a test. Fix build.