Updating Header Row to be a select field

- HTML template updated to revise Header Row from a checkbox to a select field with hardcoded options
- translation.json updated with revised tooltip copy for Header Row
- directive updated with revised default value for headerRow and removing redundant spreadsheet.sheet property as spreadsheet.url is the same
- e2e tests updated to refer to use of select field now for Header Row
- appeasing character encoding issue with e2e tests on jenkins
Merge pull request #32 from stulees/feature/update-header-rows

Updating Header Row to be a select field