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. Install build dependencies (see README.md).
4. Run sh buildpackage.sh.
juju-gui-infrastructure is private which is a little strange for a debian package, but given that these debs are going to be private, we aren't likely to get any email to them. There should be zero or near zero noise.

updated.