Tell new signups about minimum password length in registrations/new.html.erb
Only display password length warning if validatable module is included
Incorporated edits from @lucasmazza, wrote integration tests for password reminder feature
Replace 'Sign in' with 'Log in' in views, update tests
Update routes to match 'sign up'/'log in', incorporate feedback from @carlosantoniodasilva
Revert "Update routes to match 'sign up'/'log in', incorporate feedback from @carlosantoniodasilva"

This reverts commit de2a24b3d37631caaf2c95d58cbf9cd6e659071e.
Restore password length message in case of error
Merge pull request #3135 from alexsoble/master

UX feature: heads-up for new users about minimum password length