Changed License Model functions
Added ajax requests
Refactoring of license model

* Reduced the number of field to two: name and url
* Adjusted License Selector
Removed properties for this branch
Send and receive license details for auphonic productions
Added support for alternate licenses
Fallback for empty fields
MIgration for existing licenses
Added support for templates again
merge
Added migration for podcast license
Fixed typos
Merge pull request #346 from podlove/license_refactoring

License refactoring