Use [NSURL fileURLWithPath] as [NSURL URLWithString] breaks if the path contains a space.

Using a path containing a space will cause the returned URL to be nil which will stop the
socket:didConnectToUrl: delegate method from being called, which will lead to a breakdown
in the connection sequence.  This took me a while to find.
Initialize variable to silence compiler warning.
Merge pull request #1 from trojanfoe/socketUN_space_fix

Fix when the UNIX Socket path contains a space