Improve logging of HTTP connection errors
Discard incoming non-OPTIONS requests if queue is too large
Improve logging and retry behaviour on Homestead (and Homer) lookup failures
Remove rough overload control code (moved to an experimental branch
Merge up to latest dev code and do code review updates
Fix compile issues and UTs
Merge pull request #200 from Metaswitch/issue144

[Reviewer Rob] Issue144 - improvements to HTTP connection failure loggin