Add Package license stuff

- Add optional element "licenseinformation"
- The license (if set) should be shown upon the package installation
- The license (if set) should be shown upon the package update
- The license (if set) should be shown in the package details

![screen](https://f.cloud.github.com/assets/81188/1275030/bd43c528-2de0-11e3-82c4-c0153fe2240b.png)