OTAPI updates

[Michael 'Mickey' Lauer]

Hi guys,

I just pushed a couple of updates to OTAPI. The most important three things 
are:

* strip down and document the bare necessities in org.freesmartphone.GSM.PDP
* add and document Call Forwarding API in org.freesmartphone.GSM.Network
* document and update call identification API and move to 
org.freesmartphone.GSM.Network

Please catch up with your implementations :)

Cheers,

Mickey.