Describe "logging back in" so users know what to expect, know why they should come back.

1) we should make sure the user knows the codename is important (and why!)
2) give them guidance that they should come back later once they have submitted

I feel like this might be a bit too wordy, but I think this sets the expectations much better for a non-techy submitter.

Re: #479
store shared strings in variables based on feedback from @diracdeltas; fix failing tests. re: #479 #489
fix broken functional tests
prefer .format to % (nit)
use escape to compare HTML-escaped strings from templates
Merge branch 'develop' into pr/489