Enable Travis CI and Coveralls

See citusdata/cstore_fdw@b95f6d4, citusdata/cstore_fdw@0a988d6, and
citusdata/cstore_fdw@f3a56bb for more details. Will add badge once this
is confirmed working.
Make tests resilient to other ports

Missed some places that'll bite us with non-standard ports.
Fix SortList test wrapper

Turns out passing strcmp to qsort isn't possible. Added a wrapper.
Use 127.0.0.1 instead of localhost. in repair test

The latter _should_ resolve to localhost and was being used as an easy
synonym for it, but this hack isn't working in Travis. Switched to the
IP address instead, which I didn't think would work but does.
Add badges

These should probably always show the master status, but as we won't
merge these changes to master anytime soon I'm just using the generic
project badges for each service.
Merge pull request #40 from citusdata/feature-travis_integ-#24

Travis and Coveralls support

cr: @sumedhpathak