Fix touch detection test on non-touch devices
TOUCH_ENABLED is false on non-touch devices which causes our minified API test to fail when opened in a browser on a traditional destktop machine. It worked fine through the command line because apparanetly phantomjs supports touch events (ha!). Check to make sure the property is not undefined instead.
Merge pull request #962 from dmlap/bugfix/touch-detect-test

Fix touch detection test on non-touch devices