made resourcehub extensible on non BoxResourceType types
tweaks
Merge pull request #44 from box/resourcehub

Make resourcehub easier to be extended on non BoxResourceType types.
allow set redirect url in oauth webview
Merge pull request #46 from box/redirecturl

allow set redirect url in oauth webview
fix null pointer exception in BoxServerException constructor. Remove/deprecated a legacy field in BoxServerError
Merge pull request #48 from box/servererror

fix null pointer exception in BoxServerException constructor. Remove/dep...