reinsert removing_need_to_specify_requester_email

Revert "Revert "Merge pull request #30 from alphagov/removing_need_to_specify_requester_email""

This reverts commit 156bb7058fa0ae0d948e369da84906543eb62121.

Conflicts:

	Gemfile.lock
	test/test_helper.rb
adjust analytics form to work without username
redis cache: prefixing cache keys with "support-"
redis cache: host env var in application.rb