add more date formats support in datebinder

[xiaocase]

now, in play/data/binding/DateBinder.java, date format only support
these:

"yyyy-MM-dd'T'hh:mm:ss'Z'", // ISO8601 + timezone
"yyyy-MM-dd'T'hh:mm:ss", // ISO8601
"yyyy-MM-dd",
"yyyyMMdd'T'hhmmss",
"yyyyMMddhhmmss",
"dd'/'MM'/'yyyy",
"dd-MM-yyyy",
"ddMMyyyy",
"MMddyy",
"MM-dd-yy",
"MM'/'dd'/'yy"

please add more formats support, like:
"yyyy-MM-dd hh:mm:ss",
"yyyyMMdd hhmmss",
"dd'/'MM'/'yyyy hh:mm:ss",
"dd-MM-yyyy hh:mm:ss",
"ddMMyyyy hhmmss",
"MMddyy hhmmss",
"MM-dd-yy hh:mm:ss",
"MM'/'dd'/'yy hh:mm:ss"

or provider a way to add these myself if needed.