fix whitespace in QuestionsController
remove redis requirement for CSV generation

Previously, pairwise would save its intermediate CSV to redis at a specified
key, and AOI download that CSV from redis. This required that the redis
instance be shared between pairwise and AOI.

Now when a CSV is requested from pairwise, it'll save it to its database under
the specified key. AOI should then download the CSV from /exports/#{key}.

[#39385987]
add String#force_encoding for Ruby 1.8
Revert "add String#force_encoding for Ruby 1.8"

This reverts commit 7c4890d1ae94ea39229bed615b30d4313ebf8e01.
conditionally force_encoding if available
alter question#export success message
Merge branch 'csv-remove-redis'
add v3.2.0 to changelog