Update cm_strings.xml

The following strings were not translated yet.

"power_notifications_enable_summary"
"wake_when_plugged_or_unplugged_summary"
"screen_animation_style_title"
"title_qs_small_icons"
"summary_qs_small_icons"
"privacy_guard_notification_title"

Translated and added.
Merge pull request #170 from Basti1337/patch-12

Update cm_strings.xml