Add just enough to get travis to run specs and pass

Conflicts:
	nerve.gemspec
Get a spec test for the example services

This checks that we can actually construct sane objects with the JSON
examples, which gives us some confidence that the examples are still
valid and we didn't forget to update them :)
Fix up bug of still requiring zk_hosts for all backends.

Just remove the checks from the service_watcher, as the reporter already
does the appropriate data validation. Also cleanup the initalize method
in the zookeeper reporter, as it was an over-complex mash of the
initialization code moved in there from the factory method whilst
refactoring