Install SSH client tools, too

Turns out that "install an SSH server" doesn't necessarily mean "also
install an SSH client" to everyone, despite the fact that if you don't have
the client installed, rarely-used features like 'scp' don't work.
Not everything is a debian-wheezy machine
os/wheezy: Fix install_package_containing to not find files with extraneous cruft

install_package_containing /usr/bin/scp was finding libsc-dev, which contains /usr/bin/scpr.
os/wheezy: Support --proxy option

Bandwidth conservation society approved.