Bug 1073742 - Add choices to platform PositiveIntegerFields.
Use a TypedChoiceField in devhub.forms.CompatForm so that unchanged extras are detected correctly.
Merge pull request #302 from kmaglione/bug-1073742

Bug 1073742 - Add choices to platform PositiveIntegerFields.
Revert "fix import typo in `local_settings.dev.py`"

This reverts commit 0535064f963aebe3581884a38492b8ec76566690.