In order to more easily integrate xpack once it moves into the
elasticsearch repo, references to the existing x-pack-elasticsearch need
to be reduced. This commit introduces a few helper "methods" available
to any project within xpack (through gradle project extension
properties, as closures). All refeerences to project paths now use these
helper methods, except for those pertaining to bwc, which will be
handled in a followup.
Original commit: elastic/x-pack-elasticsearch@850668744c
Created a smoke-test-monitoring-with-watcher project that runs REST
tests with watcher enabled to ensure that the proper watcher are
installed either when the local or the HTTP exporter are set up.
Also removed two more watcher imports in the tests.
Relates elastic/x-pack-elasticsearch#2925
Original commit: elastic/x-pack-elasticsearch@0a9abc3185