This change allows to easily understand PDP context status changes.
The trap sent contains the following (in a comma delimited format):
status, IMSI, SAPI, NSAPI, TI, APN if found, IP address if found,
IPv6 address in case the MS has both.
Change-Id: Ie0ab550125372047e8267f008fe1dfd0cc70148a
Some level of split already existed, like sgsn_auth.c, but headers were
entangled together.
Let's clearly separate application centric code (sgsn.c/h), auth related
code (auth.c/h) and mmctx related code (mmctx.c/h).
Change-Id: I048a082851c1275c959649942904205b02acce2a