install dev packages

now, that we are compiling everything from the pip packages,
we need to install all kinds of dev libraries to get the correct
set of .h files.
modify the jenkins test script to deploy

resolves some issues with the current jenkins script.

configures virtualenv to allow falling back to the system
packages.

configures pip to still install packages, even if they are
already installed on the system.
Merge pull request #14 from bodepd/fix_package_lookups_in_script

Fix package lookups in script