Fix import of pip modules
Fix import of pip modules

when using pip versions between 10.0 and 18.1, the import of the _internal modules in pip_state will fail.

Ref pip 10.0.0b1 release notes:
https://pip.pypa.io/en/stable/news/#b1-2018-03-31

This PR changes 18.1 to 10.0

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt