Changes:
- Added a way to import source repositories from predefined lists #203
- Added some predefined source repositories lists to import (Debian, Ubuntu, Fedora, CentOS, Redhat, OpenSUSE, etc ...). It is recommended to import them to benefit from suggestions when creating a new repository. More lists may be added later.
- Added distributions and release versions suggestions when creating a new repository.
- UI improvements, contrast, colors, etc.