pootle_profile: Move profile URLs to /profiles/

/accounts/ is reserved for accounts (authentication) related urls
contributors: If the user does not have a username, treat as anonymous
Docs: bump our documented minimum Django versions

Also try document this in the requirements file and release guidelines
to catch this type of error earlier.
Docs: typo
runner: Fix the input() shim if run from `pootle'
setup.py: Use new-style exception syntax