python-packages: Add package for ecdsa library.

This is needed for the latest Paramiko release, which includes support
for ECDSA keys using this library.

I'm using ECDSA in the description itself, because the name also
reflects the functionality and "cryptographic signature library" would
sound odd in this case.

Also, I'm adding myself to maintainers, because I'm going to take over
maintenance for Paramiko as well.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>