Added methods to create, update and get user preferences
Added methods to create, update and get user preferences

crowdresearch/daemo,shirishgoyal/crowdsource-platform,crowdresearch/daemo,crowdresearch/daemo,aginzberg/crowdsource-platform,shirishgoyal/crowdsource-platform,shirishgoyal/crowdsource-platform,crowdresearch/crowdsource-platform,aginzberg/crowdsource-platform,aginzberg/crowdsource-platform,crowdresearch/crowdsource-platform,crowdresearch/daemo,crowdresearch/crowdsource-platform,aginzberg/crowdsource-platform,crowdresearch/crowdsource-platform,shirishgoyal/crowdsource-platform