Disentangle the client library from clearwater logging code
Update file headers to remove references to clearwater
Change SAS logging levels to use a enum
Update readme
Mandate a log callback
Revert contact email address
Revert contact email address
Merge master into issue7 branch for pull request
Merge pull request #10 from Metaswitch/issue7

[Reviewer: Matt, From: Alex] Disentangle SAS client library from clearwater logging infrastructure.