Add utility function to help selection
Move plot_popup to partials/ template folder
Add buttonEnabler module

fixes #376 on github.

Takes care of enabling buttons and selectively modifying their behavior based on the different states of users logged in and permissions they have.
Fix pluralization typo

 fixes #571 on github
Merge pull request #585 from steventlamb/topic/button_enabler

Topic/button enabler