Enable OS X on Travis

Remove unsupported osx.10.10-x64 moniker. Use `osx_image: xcode7.3` to
get an OS X 10.11 image on Travis.

.travis.yml

@@ -4,9 +4,10 @@ matrix:
     - os: linux
       dist: trusty
       sudo: required
-    # - os: osx
-    #   language: generic
-    #   env: PATH+=/usr/local/share/dotnet
+    - os: osx
+      osx_image: xcode7.3
+      language: generic
+      env: PATH+=/usr/local/share/dotnet
 git:
   submodules: false
 before_install:

PowerShellGitHubDev.psm1

@@ -36,7 +36,6 @@ function Start-PSBuild {
                      "win7-x64",
                      "win81-x64",
                      "win10-x64",
-                     "osx.10.10-x64",
                      "osx.10.11-x64")]
         [Parameter(ParameterSetName='CoreCLR')]
         [string]$Runtime,

src/Microsoft.PowerShell.CoreConsoleHost/project.json

@@ -37,7 +37,6 @@
         "win7-x64": { },
         "win81-x64": { },
         "win10-x64": { },
-        "osx.10.10-x64": { },
         "osx.10.11-x64": { }
     }
 }