Build-file polish
Merge remote-tracking branch 'upstream/master'
Polish
SOCIAL-308: Added logging to determine if miscommunicated provider errors is still a problem and, if so, what's triggering the problem.
SOCIAL-259: Allow callback URL to be explicitly configured instead of relying on calculation from current request. Also make callbackUrl() protected to allow for overriding when neither calculation nor explicit specification are sufficient.
Merge pull request #83 from habuma/master

Added logging in ProviderSignInController and made callback URL specification more flexible.