BUG: Fix by adding a new keyword.

The module files (cmake.module) now use a new keyword: BACKEND.
These Python scripts have been updated to incorporate this change.
The list of keywords is now sorted alpabetically.

Change-Id: I322bb5db681e04ea5a682ecb3c57d6f1f10e9362
Signed-off-by: Andrew Maclean <andrew.amaclean@gmail.com>
Merge topic 'add_new_cmake_module_keyword' into master

e6ac3bf0 BUG: Fix by adding a new keyword.