Rearrange lines on .travis.yml to see if problem really is mem/disk limit, or actually problem with Mongo DB.
Travis: Adding mongodb to services, hoping this will fix the install issue...
Travis: Clean up debugging. Trying using (python) rosdep to install requirements instead of apt-get as it appears MongoDB conflict may be breaking build.
Travis: trying different rosdep syntax.
Travis: Remove rosdep foolery; change syntax to fix sublime yaml highlighting; try to put mongodb stuff to fail first and isolate problem.
Travis: Instead of installing mongoDBs, now attempting to mark them so they won't be installed.
Try installing mongodb-client/server with -y to apt-get.
Travis: Trying to make mongodb-* install successfully...
Hopefully purge offending mongo package before installing. Also fix bug and slim down pip requirements.
Travis: Hopefully add command that will make rosmake recognize pr2_pbd stack.
Fix ros package path.
Travis: try to fix pr2_pbd_speech_recognition Manifest XML syntax error by doing an apt-get upgrade... tab-ify manifests too, though this likely won't fix anything.
Travis: Add python rospkg install to apt-get.
Travis: Attempt to install python rospkg through pip.
Add catkin-pkg to pip install.
Travis: Remove pocketsphinx as package dependency and move to apt-get install.
Travis: Realized that Traivs uses virtualenv for all Python packages, so apt-get installed python packages won't work, will have to switch over one-by-one to pip as they are discovered. Added rosdep to pip requirements.txt file.
Travis: Allow python virtualenv to use system (apt-get installed) packages.
Build finally BUILDS, trying to remove some requirements(.txt), upping time limit on test.
Up test time limit to one hour. It appears that gazebo is just taking a really long time to launch everything, and nodes are waiting for services that are ultimately bound to fail (even in local builds): forearm cameras. Perhaps the next step is trying to disable these in gazebo at all.