GPII-189: Remove fontSizeToScale transformation

[changes]
  * Removing fontSizeToScale transformation from gpii.transformer
  * Updating text-scaling-factor setting on linux.json to use the
  fluid.model.transform.binaryOp transformation
  * Setting the GNOME's default base font-size value to 11
GPII-189: Setting the GNOME's default base font-size value back to 12

This will be updated later into a separate pull request.
GPII-189: Move to the newest infusion's model transformations
GPII-177: Merging in changes from GPII-189, removing the fontSizeToScale transformer and changing the transformation in the solutionsregistry to be a binaryOp