Refs #16 - Adds pimpmytheme settings schema.
Refs #16 - Updates doc link for pimpmytheme references.
Refs #16 - Adds pimpmytheme support info in doc.
Refs #16 - Adds pimpmytheme optional but coming in next release setting PIMPMYTHEME_GIT_REPOSITORY.
Refs #16 - Added links in docs/third-party.
Added support for django-pimpmytheme settings. Closes #16.