Merge branch 'master' into dev-webhooks

Conflicts:
	orcid-persistence/src/main/resources/db-master.xml
Changed TreeCleaner so that logic for deciding whether to descend tree,
and for detecting empty elements is separate and different (previously
the same logic was, incorrectly, being used for both).
Adding method processWebhook
Merge branch 'dev-webhooks' of github.com:ORCID/ORCID-Source into dev-webhooks
Formatting
First (incomplete) attempt at parent method for processing webhooks.
Adding a http connections pool for the http requests
Doing manual merge
Adding methods signature for registering and unregistering webhooks
Adding methods signature for registering and unregistering webhooks
Added specific last_sent column to webhook, so that other kinds of
changes do not interfere with sending process.
Formatted.
Changed webhook unit test so that http client is mocked (and therefore
not dependent on current qa-1 config/status).
Added runtime config variables for number of webhook threads and retry
delay.
Updated webhook manager to use last sent date instead of last modified,
when successfully sent.
Updated webhook manager to save webhook back to DB after processing.
Added missing methods to test stub.
Mocked out webhook DAO in webhook manager test.
Corrected hashCode and equals for webhooks.
Fixed license.
Added dirties context annotation to test class, because of use of mocks.