Add all shells to Travis CI configuration

.travis.yml

@@ -4,11 +4,31 @@ matrix:
   include:
     - python: 2.7
       os: linux
-      env: _REZ_SHELL=bash
-
+      before_install:
+        - sudo apt-get install tcsh -y
+        - sudo apt-get install csh -y
+    # Travis CI does not support Python on Mac OS out of the box, this is a
+    # simple workaround until they can. More info:
+    # https://github.com/travis-ci/travis-ci/issues/2312
+    - language: generic
+      os: osx
+      before_install:
+        - brew update
+        - brew install tcsh
+        # The Python version might already be installed and has some symlinks
+        # lying around. We remove the symlinks only when the version is not yet
+        # installed of course.
+        - if ! [ brew list python@2 ] && [ -L /usr/local/bin/python2 ]; then
+          brew unlink python;
+          fi
+        # brew install errors out if the formulae is already installed, lets
+        # check and make sure we actually need to install Python.
+        - if ! [ brew list python@2 ]; then brew install python@2; fi
+        - export PATH="/usr/local/opt/python@2/libexec/bin:$PATH"
+        - virtualenv env -p python2
+        - source env/bin/activate
 install:
-  - 'if [ "$_REZ_SHELL" == "tcsh" ]; then sudo apt-get install tcsh; fi'
   - 'python ./install.py ../rez_install'
 
 script:
-  - '../rez_install/bin/rez/rez-selftest -s $_REZ_SHELL'
+  - '"../rez_install/bin/rez/rez-selftest"'