mostly run analyzer tests on travis

* [x] regonfigured the build matrix with more php jobs and a separate python job (we can add more python jobs later)
* [x] run tests on travis' trusty beta container (it's closer to what we need anyway)
* [x] install packages needed for analyzer tests in build env
* [x] added docs on how to run nosetests locally
* [x] don't run initctl in analyzer setup so setup can also be used on travis (and add it to the install script directly)
* [x] ignore replaygain checks on travis (it has proven quite impossible to get the needed python-gi module to work in the provided virtualenv)

I tried a lot of solutions to get the replaygain checks to run. I needed to decide that this has gone far enough, maybe someone who is more of a pythonista than me can take a crack at it and get it solved. Even without running those tests on CI/CD there are still plenty others.

This PR only has parts of what are needed for getting python tests running on travis as per #15. I only took a quick shot at anything not analyzer and figured I would not be able to "fix" them without digging a bit deeper (ie. also getting rid of std_err_override).

docs/TESTING.md

@@ -50,3 +50,25 @@ cd airtime_mvc/tests
 # run a subset of tests
 ../../vendor/bin/phpunit --filter testEditReatingShowInstance 
 ```
+
+## Python
+
+The python tests are run through nosetest. To prepare your env you should install
+it.
+
+```bash
+# Debian/Ubuntu
+apt-get install python-nose
+
+# CentOS
+yum install -y python-nose
+```
+
+In most cases you need to install deps before the tets can be run.
+
+### Airtime Analyzer
+
+```bash
+cd python_apps/airtime_analyzer
+nosetests
+```