add stream marker model and response objects
add StreamMarker field to Channel
add client methods for updating stream markers
add file and associated data structures
add File response handler classes
add methods for getting current user files
add @Expose annotations, constructors

only kind, type, name, and public are used when creating a file.
Merge branch 'features/File' of github.com:alwaysallthetime/ADNLib into features/File

Conflicts:
	ADNLibModule/src/main/java/com/alwaysallthetime/adnlib/AppDotNetClient.java