Take latest cpp-common
Take new rapidjson
A couple of type fixes for the new rapidjson
Fix up terrible use of MemberIterator
Merge pull request #101 from Metaswitch/rapidjson

[DON'T MERGE] [REVIEWER: AMC] Take new rapidjson
update cpp-common
Merge pull request #102 from Metaswitch/update_cppcommon

No reviewer: update cpp-common
Change Metaswitch submodule refs to ClearwaterCore