Cherry-pick of "Merge branch 'pip-1.0-20171128' into '1.0'"

Add pip to analysis releases, 1.0 branch (2017.11.28.)

See merge request !193 (merged)

(cherry picked from commit 8d0c37a4)

• 38114559 Added a module for finding pip in an LCG release, and updated
• 75bd091f Taught PyAnalysis how to build/install pip in a standalone build.
• 241c76f8 Turned off the installation of pip on macOS, as the Python version built by us