Start moving non-android specific classes into a normal java jar.

This will enable us to run unit tests on a normal jvm, which is much
faster than the emulated android jvm.
Remove boilerplate class.
Merge branch 'wip/uploaders-to-core' into dev

Conflicts:
	app/build.gradle
	app/src/main/java/com/nightscout/android/upload/Uploader.java
	core/build.gradle
	core/src/main/java/com/nightscout/core/upload/BaseUploader.java
	core/src/main/java/com/nightscout/core/upload/MongoUploader.java
	core/src/main/java/com/nightscout/core/upload/RestLegacyUploader.java
	core/src/main/java/com/nightscout/core/upload/RestV1Uploader.java
	core/src/test/java/com/nightscout/core/upload/AbstractRestUploaderTest.java
	core/src/test/java/com/nightscout/core/upload/BaseUploaderTest.java
	core/src/test/java/com/nightscout/core/upload/MongoUploaderTest.java
	core/src/test/java/com/nightscout/core/upload/RestLegacyUploaderTest.java
	core/src/test/java/com/nightscout/core/upload/RestV1UploaderTest.java