Add check for momentProperties to avoid uncaught exception

I had an error where it said _z is undefined. This took me about 5 minutes to breakpoint the code, which lead me back to the site where I found moment 2.6 was required. Because this threw an uncaught error other items broke like not being able to load data. By having if statement you get the benefit of

1 - No uncaught exception where user is confused
2 - User gets a helpful message in their console and a link to correct the dependency

Thanks for the great library!