Updated DEB build workflow

Updates to Makefile include:
 * add targets: deb-src, deb-src-upload, deb-upload
 * add variables to control DEB building: DEBUILD_OPTS, DPUT_OPTS, DEB_PPA, DEB_DIST, DEB_RELEASE
 * create deb files for all release values in DEB_DIST

Several updates to packaging/debian/*
 * Updated control file
 * Whitespace/formatting of changelog

Add deb-build to .gitignore