Move httpstack and httpconnection into cpp-common
Update httpstack with changes from the UTs
Merge remote-tracking branch 'origin/httpstack_cppcommon'
Add Httpstack methods to retrieve method and body
Allow bodies larger than 1024 bytes
Merge branch 'master' into http_body
Merge pull request #10 from Metaswitch/http_body

[Reviewer: Andy] Http body