Licensing

In the utils 1.6.0 release, we've a new license module which can be used to create and read/verify licenses.

Let's use that module and build a proper Django middleware which validates the license of a project / product. We should probably read the key from the settings file or do some "obscure magic" by defining the key from the package name or alike by default.

What the license middleware must ensure is:

• That there's a valid license on the filesystem
• The path for the license file should be determined via settings with a default fallback
• In case the license is not valid, it must intercept the response and display an error
• The software should be rendered unusable when there's no license
• The only exception is DEBUG mode & local access (so that developers need no license)