Updates to accommodate spreadsheet selection functionality

- Fix to gulp "angular" task to correct order of concatenation of files
- Directive injecting Google Drive Picker, adding "url" prop to scope, listening for Google Drive Picker "picked" and "cancel" events, and general format cleanup
- Template now includes a small element for displaying validation error, a div well for eventually placing spreadsheet hyperlink, and now hiding containing div of range field instead of disabling
- Test HTML updated to point to updated common-style repo for css
- Test scenarios updated to check for displayed instead of disabled on range field