Build on Yosemite as well

Yosemite does not come with pip, so it has to be installed.

.travis.yml

@@ -1,4 +1,4 @@
-language: c
+language: python
 
 matrix:
   include:
@@ -8,13 +8,23 @@ matrix:
       env:
         - RELEASE=trusty
     - sudo: required
-      env: RELEASE=precise
-    - os: osx
+      env:
+        - RELEASE=precise
+    - language: c
+      os: osx
       osx_image: xcode8.2
-      env: RELEASE=sierra
-    - os: osx
+      env:
+        - RELEASE=sierra
+    - language: c
+      os: osx
       osx_image: xcode7.3
-      env: RELEASE=elcapitan
+      env:
+        - RELEASE=elcapitan
+    - language: c
+      os: osx
+      osx_image: xcode6.4
+      env:
+        - RELEASE=yosemite
 
 env:
   global:
@@ -32,12 +42,16 @@ install:
     brew uninstall pyenv
     brew install pyenv --HEAD
   fi
+  if ! python -m pip >&/dev/null; then
+    wget https://bootstrap.pypa.io/get-pip.py
+    sudo python get-pip.py
+  fi
 - sudo -H python -m pip install virtualenv --upgrade
 
 before_script:
 - 'export INSTALL_DEST=${INSTALL_DEST:-/opt/python}'
-- 'export LSB_RELEASE=${LSB_RELEASE:-$(lsb_release -rs || echo ${$(sw_vers -productVersion)%*.*})}'
-- 'export OS_NAME=${OS_NAME:-$(lsb_release -is | tr "A-Z" "a-z" || echo "osx")}'
+- export LSB_RELEASE=$(lsb_release -rs 2>/dev/null || sw_vers -productVersion | sed 's/^\([0-9][0-9]*.[0-9][0-9]*\).*/\1/')
+- 'export OS_NAME=$((lsb_release -is 2>/dev/null || echo "osx") | tr [[:upper:]] [[:lower:]])'
 - 'export ARCH=${ARCH:-$(uname -m)}'
 - 'export PACKAGES=${PACKAGES:-pip nose pytest mock wheel}'
 - 'export CPYTHON_ONLY_PKGS="numpy"'