add ccdict.go for Credit-Control Applications
rename variables to be more descriptive
add credit_control dictionary from http://tools.ietf.org/html/rfc4006#section-8
add Credit-Control Request and Credit-Control Answer messages to credit_control dictionary
Merge branch 'cc_dict'
Revert "Add some AVPs for CCR"

This reverts commit e915deb9b30a23389e214b3fcdc905ba41533868.

Conflicts:
	examples/client/client_beeline.go