version_url and regex can be null, it will even be the case for most backend
Fix the API where it was relying on the package to provide the url and regex instead of the project
Small code formatting for a query
Fix setting up the test environment correctly
Start porting the API unit-tests to Anitya and its new structure/data
Move the backends/plugins into lib
Add a generic exceptions class that can be thrown by the different backends
Move the plugin manager module in the lib
Adjust loading the backends
Adjust loading the backends in the plugin manager
Adjust the get_version API as plugins may throw an exception in case of error
Fix import of the plugins module
Fix import of the model in the tests
Adjust imports of the plugins and exceptions and fix the catch of the exceptions
Handle the situation where no backend was found with the settings stored in the DB
Adjust the test project unit-tests
Allow the saving of the plugin in the DB to fail (required for the unit-tests)
Fix import of the model in the tests
Fix imports which fixes loading the plugins/backends
Load all the plugins presents for the unit-tests