* implemented missing 'delete' push webhooks
moreover created ActionDeleteBranch and ActionDeleteTag
* add CommitRepoAction tests for tag/branch creation/deletion
* fixed error where push webhook not called if is new branch or tag
removed unnecessary code
* moved prepare unit test environment into separate method to be used across unit tests
* add missing if clause in pushUpdate
Signed-off-by: David Schneiderbauer <dschneiderbauer@gmail.com>