Adds migration file that creates  passing unit tests

The migration file changes the add_index on the email and password
fields that were required to be unique in our database. This will be fine
for now while we are testing the application. When we are ready for a
release build of this app, we will need to re-enable those properties.

Additional changes were made in the fixtures file,  job_postings_controller
test file, and the job_posting_test file (the model test). Most of these changes
changed camel cased class properties to snake cased properties to match what
was in our database schema.

All new tests should be passing with the exception of the two controller tests
which are currently not passing.