Add BPM annotations to mark methods as process action triggers

Per the discussion in the Forum Reference (see jira link), adding @StartProcess, @SignalEvent and @AbortProcess method-level annotations would allow the developer to declaratively designate which service invocations will result in what type of process action to trigger.

If this is done, then incoming SOAP requests (if the SOAP Component is the gateway) would not be required to have bpm-specific SOAP headers to designate which processAction to trigger.

Additionally, the @BPM class-level annotation should change to @Process to maintain consistency in naming, and all 4 annotations should move to a new org.switchyard.component.bpm.annotation(s?) package.