puhh. this is a big commit

- change the complete file sending / receiving process between phone and watch, we now use channels instead of simple messages. this is recommentad by google, due to some changes in google play services.
- made some smaller changes in the ui, for file saving and saving of sensordata for evaluation purposes
- edited the manifest and gradle script for play store.
- made some change for a better performance for he huawei watch

android/ConductorsWatch/gradle.properties

@@ -10,6 +10,7 @@
 # Specifies the JVM arguments used for the daemon process.
 # The setting is particularly useful for tweaking memory settings.
 org.gradle.jvmargs=-Xmx1536m
+android.enableD8=true
 
 # When configured, Gradle will run in incubating parallel mode.
 # This option should only be used with decoupled projects. More details, visit