Scratch-www: Teachers and students can no longer sign up; an error occurs.

[BoomerScratch]

Teachers can no longer sign up. As of this bug report, the same happens with students. It appears that the API request gets sent to the wrong URL. It should be https://api.scratch.mit.edu/accounts/checkusername/USERNAME, but instead, it gets sent to https://scratch.mit.edu/accounts/check_username/USERNAME/.

Steps to Reproduce

Go to the teacher registration or to the student registration, and type in a username.

Operating System and Browser

all?

[BryceLTaylor]

This has been fixed.