Selectable job lifecycle events, SCM information, Artifacts URLs

New features:
* It is now possible to select job lifecycle event to trigger notification - job started, completed, finalized or all of them (the default behavior).
* Scm information is reported - url, branch, commit. Only Git is supported so far.
* Artifacts information is reported - Jenkins (if archived) and S3 (if uploaded to S3) URLs.
Improvements:
* When defining an endpoint - default endpoint timeout (30000) is pre-filled in a form.
* When defining an endpoint - protocols order in  a dropdown is changed to HTTP, TCP, UDP.
* Endpoint URL validation error now includes the faulty URL if it's not empty.
* Correct "Content-Type" header is sent, according to XML or JSON payload submitted.
* POM dependencies updated.
* Various IDEA warning were eliminated, like proper sorting of access modifiers.
* Tabs are replaced by 4 spaces.
@hagzag , what do you say?