DateTimeRangeWidget: change default labels, document label options
DateTimeRangeWidget: change default labels, document label options

kotfic/girder,manthey/girder,adsorensen/girder,salamb/girder,Xarthisius/girder,essamjoubori/girder,essamjoubori/girder,salamb/girder,kotfic/girder,opadron/girder,jbeezley/girder,manthey/girder,sutartmelson/girder,data-exp-lab/girder,adsorensen/girder,data-exp-lab/girder,manthey/girder,essamjoubori/girder,msmolens/girder,adsorensen/girder,data-exp-lab/girder,Kitware/girder,opadron/girder,sutartmelson/girder,RafaelPalomar/girder,adsorensen/girder,msmolens/girder,msmolens/girder,sutartmelson/girder,data-exp-lab/girder,RafaelPalomar/girder,salamb/girder,essamjoubori/girder,kotfic/girder,jbeezley/girder,Xarthisius/girder,jbeezley/girder,Kitware/girder,opadron/girder,Xarthisius/girder,jbeezley/girder,adsorensen/girder,Kitware/girder,sutartmelson/girder,salamb/girder,data-exp-lab/girder,kotfic/girder,RafaelPalomar/girder,girder/girder,kotfic/girder,manthey/girder,RafaelPalomar/girder,girder/girder,RafaelPalomar/girder,Xarthisius/girder,girder/girder,essamjoubori/girder,opadron/girder,Xarthisius/girder,Kitware/girder,sutartmelson/girder,salamb/girder,girder/girder,msmolens/girder,msmolens/girder,opadron/girder