Add maintainers file

[thijs]

We should publish the actual list of committers. The traditional place for this is a file called MAINTAINERS or COMMITTERS in the top level of the project's source code tree. It should list all the full committers first, followed by the various partial commit domains and the members of each domain, which we omit in the case of PyAMF (until it's necessary). Each person should be listed by name and email address, though the address can be encoded to prevent spam if the person prefers that.

[thijs]

Fixed in r1408