Django Models - ExtraCredit

[creinkin]

Use the ERD on the base readme of the repo to develop the ExtraCredit django model:

Do the following steps to complete the implementation

1. Fill in the models.py with the model definition
2. Register the model with the admin interface
3. Overwrite the __str__ function to create a nicely formatted string to represent the object
4. Make the migration for the model change (IMPORTANT NOTE: To not have migration naming conflicts between concurrent work, migrations should use the ‘name’ option available to the command https://docs.djangoproject.com/en/1.9/ref/django-admin/#cmdoption-makemigrations--name)
5. Use git to commit and push all changes/new files to github master branch.
6. Add label of 'ready to review' on this GitHub Issue for review by @creinkin

[creinkin]

Blocked by #1 and #2. Can be worked after those are implemented.

[creinkin]

There is duplication of effort in your __str__ function. You are essentially duplicating the Developer and Skill __str__ function rather than utilizing what has already been written.

Please fix this and recommit to close this issue.