"The Word" or Added validation and storage of student language fields

This change follows pull request (branched from there) #142 .

This covers the BE tasks for #109 .

None of the fields were submitting correctly in the PUT, so it required changes to the ERB template too. There appears to be an issue with the radio buttons for having had English language instruction (this may be related to the radio button issues seen in other tickets). The radio button selection can be made once and then does not seem to change. Also, the same radio buttons require styling, but I didn't want to touch it until the radio button issue is solved in case it required any rework.

@codesliced Ready for review.