Import config file generator module from python path

The sample config file generator will be executed in each project's
virtualenv after being copied using the update.py module. Therefore
accessing the generator module would not work the current way
of using relative paths. This patch executes the generator module
by directly importing it. The update.py will update the module path
when copying to each project.

Change-Id: Id40422ae170935d2fc1c7443eee4b31161b7d3d3
Merge "Import config file generator module from python path"