Update reduced Datums for existing Target via data service

[jchate6]

This needs to happen in two places:

• We need to be able to get new Reduced Datums from the Target Detail page
  • Allow Query Reduced Datums to get_or_create
  • Build test to make sure we aren't replicating data
  • Update Documentation
  • Implement UI methods to update data
    • Use "Update Data" Button on Phot tab
    • Add Data Service Query from Manage Data Tab
• When adding a target with new data from a data service, the Reduced datums should be updated.
  • Add message that data have been updated even though the target already existed