spamming the submit button causes multiple roommate search items to be created

[ad6641]

account used: test_user_1

when I am on the create roommate post page
http://django-tutorial-test-before-deploy2.eba-n75bixnu.us-west-2.elasticbeanstalk.com/roommates/

I enter values that are allowed by the form, and then spam the submit button until the page refreshes and takes me to the post details page.
Then, when i navigate to the listings page:
http://django-tutorial-test-before-deploy2.eba-n75bixnu.us-west-2.elasticbeanstalk.com/roommates/

i see many identical posts.

Expected behaviour:
the button becomes disabled once we click it once, and/or there is a listing ID that prevents multiple creations of the same listing.