Rewrite python/Makefile
Rewrite python/Makefile

* Remove upgrade-python (it's better to use a virtualenv)
* Remove check-fast (not working)
* check: use -n `nproc`
* Fix doc
* Remove using MYPYMODULES to limit the modules to run tests on
  (it's simpler to use py.test directly)

Change-Id: I7317a90c858ca47e4f3734a1a886e475a0e69dd7
Removed:
Reviewed-on: http://gerrit.aldebaran.lan/58043
Tested-by: gerrit
Reviewed-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>
Tested-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>

aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild