Panel translation fragments (#691)

* Move flatten to separate gulp task

* Split translation fragments into separate files

* Load translation fragments when switching panels

* Fix gulpfile lint

* Move app-location to home-assistant.html

* Compute panel navigation in home-assistant.html

* Only pass down panelUrl from home-assistant.html

* Store panelUrl on hass

* Store computed panel on hass object

* Revert "Store computed panel on hass object"

This reverts commit 0f150b1faa2b91588a432ab346821b633b349d1a.

IMO this didn't really make the code cleaner. Just wanted to see how it
would look. Keeping it here as a reverted commit in case we do want to
use it.

script/build_frontend

@@ -28,8 +28,7 @@ mkdir $OUTPUT_DIR_ES5/panels
 cp build-es5/panels/*.html $OUTPUT_DIR_ES5/panels
 
 # Translations
-mkdir $OUTPUT_DIR/translations
-cp build-translations/*.json $OUTPUT_DIR/translations
+cp -r build-translations/output $OUTPUT_DIR/translations
 
 # Local Roboto
 cp -r bower_components/font-roboto-local/fonts $OUTPUT_DIR
@@ -60,6 +59,7 @@ gzip -f -n -k -9 \
     *.js \
     ./panels/*.html \
     ./translations/*.json \
+    ./translations/*/*.json \
     ./fonts/roboto/*.ttf \
     ./fonts/robotomono/*.ttf
 cd ..