Return all columns from cassandra rather then the first 100
Firewall against updating of already expired cache entries that have outstanding references
Merge pull request #175 from Metaswitch/http_perf_fixes

[Reviewer: Ellie] Return all columns from cassandra rather then the first 100
Change blacklist to use simple map
Code review updates
Merge pull request #176 from Metaswitch/issue739sprout

[Reviewer Andy] Issue739sprout