maint - add travis CI configuration

Here we tweak the Gemfile to be consistent with the other projects, and load
up the correct gem (mcollective-client) as a dependency.
maint - fixup tests to stub dataquery_interface

Since version 2.3.2 (25160d88) it's been neccesary to stub out
ddl.dataquery_interface.  This commit adds that mocking to enable
the tests to run again.
Merge pull request #7 from richardc/add-travis

Add travis configuration and fixup tests