Fix typos in agent files (#640)

Author: isaachier

…d/agent/app/reporter/tchannel/bulider.go …d/agent/app/reporter/tchannel/builder.gocmd/agent/app/reporter/tchannel/bulider.go renamed to cmd/agent/app/reporter/tchannel/builder.go cmd/agent/app/reporter/tchannel/bulider.go renamed to cmd/agent/app/reporter/tchannel/builder.go

@@ -33,7 +33,7 @@ type ReadBuf struct {
 	n     int
 }
 
-// GetBytes returns the contents of the Readbuf as bytes
+// GetBytes returns the contents of the ReadBuf as bytes
 func (r *ReadBuf) GetBytes() []byte {
 	return r.bytes[:r.n]
 }