histograms: dimuon/Jpsi updates

* Removes extra dimuon file and fixes Jpsi file name. (PR #419)
histograms: file menu selection update

* Updates file menu to show selection and to rm csv displayed.
  (closes #398) (PR #419)
histograms: parameter information

* Adds description and units for each parameter in the button title.
  (closes #381) (PR #419)