add trailing slash to currentUserUrl

[gumaerc]

What are the relevant tickets?

Closes #4

Description (What does it do?)

This PR simply adds a trailing slash to the the API URL hitting /apiv/0/users/me to avoid a 301 redirection. 301 redirection breaks CORS requests, so this is necessary for the API request to not trigger a CORS error.

How can this be tested?

• In order to test this, you will need a running instance of mit-open. Follow the instructions in the mit-open readme for initial setup. You will need an account in your local instance for this to work. Your instance of mit-open should be accessible at http://od.odl.local:8063. You will need to set the following environment variables:

CORS_ALLOWED_ORIGINS=["http://ocw.odl.local:3000"]
SOCIAL_AUTH_ALLOWED_REDIRECT_HOSTS=["ocw.odl.local:3000"]

• You will also need ocw-hugo-themes (https://github.com/mitodl/ocw-hugo-themes) set up locally, running a course using yarn start course. Follow the readme there for basic setup instructions and make sure you can start up a course. After you have that working, check out the cg/add-mit-open-login-button branch. Assuming you have cloned this repo, run yarn add /path/to/mit-open-login-button to add your local copy of the code for this to your locally running ocw-hugo-themes. This is necessary because the package is not yet published to NPM. You will also need an entry in your hosts file that points the ocw.odl.local domain to 127.0.0.1.
• Once you have all this running, make sure you are logged out of your local instance of mit-open
• Back in your locally running OCW course site, you should see a Login button in the upper right. Click this button and log in to your locally running mit-open
• After you have logged in, you will be sent to http://od.odl.local:8063
• Go back to your locally running OCW site at http://ocw.odl.local:3000 and confirm that you see Logged in as: username with your username in place of username
• In another tab, log out of your locally running mit-open
• Verify that the login button reappears

[ChristopherChudzicki]

👍 This worked for me. However, I just used

• http://localhost:8063 for MIT Open
• http://localhost:3000 for OCW

Which worked fine. I opened mitodl/ocw-hugo-themes#1310 to facilitate sharing this work within the team.