Community: Administer packages

[boazpoolman]

Community members will be able to administer their packages to a certain extend. They should be able to do at least the following:

1. Add new maintainers to their package
2. Hand over ownership of their package to another user
3. Archive their package

There are certainly more things that we could allow them to edit. Let's see if it's worth the time investment. For example for the following things they could also quickly contact us to make the change:

1. Update the package name
2. Update the Github repo URL
3. Update the package location URL