Initial AKA changes
Implement AV store for AKA
More AKA code
Fixes to get Digest authentication working
Add support for the autn parameter
AuthVector store implemented on top of memcachedstore
Remove obsolete headers
Merge dev in to aka branch
UT fixes
Fix merge issue
UT compile issues
Fix up unit tests
Fixes to get AKA working with SIPp
AKA fixes and unit tests
Authentication module fixes and UT to 100%
Move up to latest cpp-common with compiler warning fixes
Move up to latest cpp-common
Merge pull request #339 from Metaswitch/cpp-common

[No reviewer required] Pull in latest cpp-common after updates to get chronos and homestead-ng building with it
Fix stale challenge response handling
Fix S-CSCF policy for selecting authentication algorithm