Major Logging Overhaul

in this commit:

- centralize logging output handler.
- set global Info/Debug/Error log levels based on config file or flags.
- remove per-plugin debug arg handling.
- add a I!, D!, or E! to every log message.
- add configuration option to specify where to send logs.

closes #1786

internal/internal.go

@@ -198,7 +198,7 @@ func WaitTimeout(c *exec.Cmd, timeout time.Duration) error {
 		return err
 	case <-timer.C:
 		if err := c.Process.Kill(); err != nil {
-			log.Printf("FATAL error killing process: %s", err)
+			log.Printf("E! FATAL error killing process: %s", err)
 			return err
 		}
 		// wait for the command to return after killing it