Moved logging to use package level logger. Disabled by default.

common.go

@@ -0,0 +1,18 @@
+package sshrpc
+
+import (
+	"io"
+	"io/ioutil"
+	"log"
+)
+
+var logger *log.Logger
+
+func init() {
+	logger = log.New(ioutil.Discard, "sshrpc", 0)
+}
+
+// EnableLogging enables logging for the sshrpc library
+func EnableLogging(output io.Writer) {
+	logger.SetOutput(output)
+}