Start of a debian package for charmstore

PR:
1. Edit buildpackage.sh and change the last line to a PPA to which you can write. 
2. Make sure you have DEBEMAIL set for signing.
3. Run sh buildpackage.sh
The charmstore charm, also needs binaries from the charmstore-client (charmload).
Are we making another deb for that? Other wise, we could do something similar to what's done by the charmstore charm's "make binaries": start from the client, the server is installed as a dependency, grab the binaries, also grab ES definitions, create the tarball.

Related: do we need all the sources to be included in the package? Or do we just need what's in $GOPATH/bin?