Added support for IPv6 IP address for the server

In Play Framework 1.2.x if you tried to use an IPv6 address for the server, you would end up with the following error:
2014-04-10 12:35:36,823 ERROR ~ 
java.lang.NullPointerException
at play.server.PlayHandler.serve500(PlayHandler.java:743)
at Invocation.Message Received(Play!)

For example, try localhost for a local server running with http://[::1]:8000

What happens is it sees the colon in the IPv6 address and attempts to parse the part of the address as the port. This fix allows parsing the host/port property when using IPv6 IP addresses.