Use pip provider to install using pip
Use pip provider to install using pip

These execs were introduced in 6a484ff89 to avoid redownloading
eggs. The pip provider has since changed to use `pip freeze` to avoid
downloading eggs for modules which have already been installed
locally, so these exec resources can revert to package { provider =>
pip} resources.

gds-operations/puppet-graphite,garethr/garethr-graphite,3fs/puppet-graphite,garethr/garethr-graphite,3fs/puppet-graphite,gds-operations/puppet-graphite