Allow data for future dates to be uploaded via data sources

[#1]

currently we can only upload data for dates that have already occured in data sources. I want to upload targets for specific metrics for future dates. This would give me the ability to compare actual performance easily against targets directly in the tool.

[#2]

In addition, please allow setting of props for datasource uploads (not only evars).

[#3]

This should be removed!! My business is begging for this functionality and its so easy if that restriction wasn't on there...