Add support for ROS Service client
Refactored PkgBuilder
CPP guard ErrorCall Eq instance

This instance was added in GHC 7.8 (base 4.7), so we only need to define
it when building with an older GHC.
CPP guard the hiding of Prelude.join

In GHC 7.10, "join" will be exported by Prelude, so we will have to hide
that import in Topic.hs where we define a "join" for Topics.
Don't run the service tests on Travis-CI
Bumped roshask major version
Merge ROS Service support
Vagrant setup tweak.