Encoder 4 Not Working with BB-Blue

```
var rc = require('roboticscape');

rc.initialize();
rc.state("RUNNING");
rc.motor("ENABLE");
rc.motor(0.3);

setInterval(function(){
console.log("encoder 1 = " + rc.encoder(1));
console.log("encoder 2 = " + rc.encoder(2));
console.log("encoder 3 = " + rc.encoder(3));
console.log("encoder 4 = " + rc.encoder(4));
}, 1000);
```
My roboticscape version:
roboticscape@0.0.8
└── nan@2.5.1

LibRobotControl Version:
Version: 1.0.4-git20190227.1-0rcnee0~stretch+20190327

This code is raising me the following error:

`ERROR in rc_encoder_pru_read, call rc_encoder_pru_init first`

Start with the reported rc.encoder(4) call and the initialization sequence in the example; check how rc_encoder_pru_init is expected to relate to rc_encoder_pru_read on the BeagleBone Blue. Done means encoder 4 can be read without the reported error under the stated roboticscape and LibRobotControl versions.

Written by the indexing model from the issue text.