Make subscriptions logs less aggressive
Use individual SAS events
Merge pull request #908 from Metaswitch/subscriptions

[Reviewer: Matt] Make subscription logs less aggressive
Merge pull request #909 from Metaswitch/reason_strings

[Reviewer: Matt] Use individual SAS events
Update references
Merge branch 'dev' of github.com:Metaswitch/Sprout into http_fail
Merge pull request #913 from Metaswitch/http_fail

[No reviewer] Http fail