Modifying .NET Firefox driver to only look to connect to IPv4 addresses.

ConnectToBrowser() always creates IPv4 addresses to initially connect on.
If an IPv6 address was found in discovering potential IP addresses for
connection, this would throw an exception. Fixes issue #4629.
Changing .NET FirefoxBinary timeout property to use TimeSpan.

Using TimeSpan allows more flexibility for the user to set, and does not
hard-code milliseconds as the unit of measure. This commit introduces
overloads of the appropriate exposed properties and methods, marking those
taking a long as obsolete. The obsolete members will be removed in a
future version.