changed _kmq declaration

The code was breaking when running tests with Karma.  It works fine with the app tho.  But while running Karma, it wasn't finding the _kmq array at all.  Even when I tried to inject it into the tests.  I was getting the following error: 

ReferenceError: Can't find variable: _kmq
        at /usr/local/web/src/src/vendor-bower/angulartics/dist/angulartics-kissmetrics.min.js:6

By changing the way this variable is declared allowed me to successfully run and test the code.