MB-22231: Use RAII for ep-engine entrypoints
MB-22231: Use RAII for ep-engine entrypoints

Adds a function to get a resource handle (unique_ptr) for
EventuallyPersistentEngine rather than a bare pointer. This resource
handler has a custom deleter that calls releaseHandle() rather than
doing a delete.

The entrypoints to EP-Engine have all been changed to use the new
style. As such the old {get,release}Handle has been removed.

Change-Id: Ic10fd7b1a693fc31de5ca7998f38976b185cfc8a
Reviewed-on: http://review.couchbase.org/72281
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

daverigby/kv_engine,daverigby/kv_engine,membase/ep-engine,daverigby/ep-engine,daverigby/ep-engine,membase/ep-engine,daverigby/ep-engine,membase/ep-engine,daverigby/ep-engine,couchbase/ep-engine,daverigby/kv_engine,membase/ep-engine,daverigby/kv_engine,couchbase/ep-engine,couchbase/ep-engine,couchbase/ep-engine