DNN-5927: fixed userfile manager dialog popup
DNN-5791 and DNN-5930 Added improved error handling
GetPortalSetting and GetPortalSettings were updated to only return a single value for each setting regardless of the number of cultures are present.  Also added better handling around the settings dictionary in PortalController to detect duplicates and only store the latest one.
Merge pull request #167 from jbrinkman/DNN-5791

DNN-5791 and DNN-5930 Added improved error handling