Update Battery widget plugin (#311)

* fix: invalid check in getWarningThreshold

* fix: invalid status

* feat: use dbus events instead of polling

* fix: invalid status again

* fix: dump version and set valid plugin API

* fix: add commandExists check

* fix: getColor function (warning color when not charging)

* feat: use upower instead of cat /sys

* feat: notify on error

* fix: cleaner code

* fix: use noctalia.tr for notification (not logs, intended)

* feat: migrate from dbus-monitor to gdbus (everything in one line)

* feat: use gdbus to init and update, parse only when needed

* feat: add label_content and optimisations

* fix: remove multiple commands check not needed anymore

* fix: update README and dump version

* fix: default data, warning_threshold check, floor percent

battery-widget/translations/en.json

@@ -48,6 +48,16 @@
     "warning_color": {
       "description": "Color applied when charge is at or below noctalia's warning threshold.",
       "label": "Warning Color"
+    },
+        "label_content": {
+            "label": "Label Content",
+            "description": "What the battery label shows: charge percentage, time remaining, or power draw.",
+            "percent": "Percent",
+            "time": "Time",
+            "rate": "Rate"
+        }
+  },
+    "notify": {
+        "error": "Something went wrong. Check the Noctalia log for details."
     }
-  }
 }