Cleaning and bug fixes

Using temporary c buffer while packing asn1 message. In some cases
at least in unittests, some go strings were corrupted during
subscription delete request pack. Root cause was not found,
but after using c buffer things did stablized.

Change-Id: I22b0af72209e2958a9844113f1d35a0d31213b92
Signed-off-by: Juha Hyttinen <juha.hyttinen@nokia.com>