continued reworking interfaces

continued reworking interfaces

removed channels from the content services implementations
  removing the chan getter code
put channel logic in to the mux logic

made interfaces for the content services witch enables the use of content
  service instances and constructors to simplify service life cycle

use Public and Private key types to reduce coupling to edas/elliptic
as well as added additional hex and marshaling functions to reduce coupling to encode

unified the content object code to a single file

added new content service using Google Apps Script