Registering NFC-Forum tags in the PushRegistry

[josergc]

For making this, the correct strings for the static registration are:

* for Text tags
MIDlet-Push-X: ndef:rtd?name=T, MIDletClassName, filter

* for URL tags
MIDlet-Push-X: ndef:rtd?name=U, MIDletClassName, filter

* for SmartPosters tags
MIDlet-Push-X: ndef:rtd?name=Sp, MIDletClassName, filter

The registration can be done through the "PushRegistry.registerConnection(String connection,String midlet,String filter)" as well. This other method is more convenient to detect if there is another other MIDlet which is already managing the same connection that we are going to register and then we can manage this issue by our-selves.