Add check for momentProperties to avoid uncaught exception
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!
rollbar/moment-timezone,kidaa/moment-timezone,d0rc/moment-timezone,samjoch/moment-timezone,moment/moment-timezone,mkhuramj/moment-timezone,lookfirst/moment-timezone,timrwood/moment-timezone,bcbroussard/moment-timezone,blixt/moment-timezone,mj1856/moment-timezone,6ft-invsbl-rbbt/moment-timezone,dieface/moment-timezone,HubSpot/moment-timezone,moment/moment-timezone,eddywashere/moment-timezone,orocrm/moment-timezone,andrewchae/moment-timezone,almamedia/moment-timezone