Change PPA and RTA functions to only accept PPRs and RTRs as args, not any generic Diameter Messages
Correct white space errors, spelling, and punctuation
Take new cpp-common, and keep _stack as NULL in the UTs until it's properly started (so we don't call stop_stack on a half-initialised one)
Fix unit tests to work on updated RTAs and PPAs
Markups
Merge pull request #121 from Metaswitch/Answer_Changes

[Reviewer: Andy] Answer changes
Code review feedback
Merge pull request #120 from Metaswitch/local_bind_bugfix

[Reviewer: Alex] Take new cpp-common, and keep _stack as NULL in the UTs until it's prope...