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.
Or it could just be a parameter the datepicker accepts to enable/disable strict parsing?