Adapt ServerTracerImpl to use CommonAnnotationSubmitter.
Add BinaryAnnotation support with String value to CommonAnnotationSubmitter.
Extend AnnotationSubmitter interface to add support for submitting binary annotation with String value.

Also implement functionality in ServerTracerImpl and ClientTracerImpl.
Make BravePreProcessInterceptor more relaxed so that is will start a new span when no span information was provided by client.

This means we will have a span with only server side annotations (sr,
ss). But that works also.