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.
The reason I have put this in is because for the date "05/05/45" `moment("05/05/45", "DD-MM-YYYY")` successfully parses this as "05/05/0045" rather than failing or returning the intended date of "05/05/2045". So if the date format is specified as `["DD/MM/YYYY", "DD/MM/YY"]` it will successfully parse the date with the first format and not try the second one, even though the date is clearly incorrect.

The only way I found to solve this is to enable strict parsing.

I'm not sure what issues the strict parsing would have in other cases however - so maybe it would be best to just enable it for arrays.