Re #28: rename bootstrap-overrides/variables.less as uw-variables.less
Re #28: import original bootstrap variables
Re #28: remove bootstrap-overrides/ dir and move its files to uw-ui-toolkit/ with the prefix uw-
Re #28: Place calls to custom uw-* styles right under original imports
Re #28: Add comments
Re #28: add newly moved files
Re #28: update comments
Merge branch 'task_28' into develop