Do more checks on the reg data from the HSS
Use rapidjson when writing acrs
Use rapidjson in acr UTs
Don't include parsing changes in pr
Merge branch 'dev' of github.com:Metaswitch/sprout into iss559
Merge pull request #889 from Metaswitch/iss559

[Reviewer: Andy] Build ACRs with rapidjson
Updates after review
Merge branch 'dev' of github.com:Metaswitch/sprout into iss591
Merge pull request #878 from Metaswitch/iss591

[Reviewer: Matt] Do more checks on the reg data from the HSS
Add UT for xml escape function
Merge pull request #892 from Metaswitch/xml_escape

No reviewer: Add UT for xml escape function
Merge remote-tracking branch 'origin/dev' into memento-stats