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
Add support for unconditionally deleting items from the store
Merge pull request #10 from Metaswitch/http_body

[Reviewer: Andy] Http body
Fix indentation
Add diameterstack from Homestead to cpp-common
Added JSON value builder to AVP
And the cpp file
Merge pull request #13 from Metaswitch/commonalize-diameterstack

Reviewer Rob - Commonalize diameterstack
Code review feedback - delete from the read replicas
Merge pull request #12 from Metaswitch/deletion

[Reviewer: Andy] Add support for unconditionally deleting items from the store
Various fixes to support RTR and PPR handling
Merge pull request #14 from Metaswitch/ppr-rtr-support

[Reviewer Graeme] Various fixes to support RTR and PPR handling
Add Acct-Interim-Interval to the AVPs list
Make val_json() easier to use
Merge pull request #16 from Metaswitch/acct-interim-interval

[Reviewer: Andy] Add Acct-Interim-Interval to the AVPs list