Allows use of an array of date formats

Moment.js allows use of an array of date formats when parsing dates.

This means that you can do... `moment('05/05/1945', ['dd/mm/yyyy', 'dd-mm-yyy'])` and `moment('05-05-1945', ['dd/mm/yyyy', 'dd-mm-yyy'])` and both will work. Moment will keep trying the formats in the array until it finds the correct one to parse it with.

I have updated the date picker to accept an array for the 'format' parameter. It then uses the first format in the array as the display format.