Add eth0 sysinfo backend

src/sysinfo/eth0.js

@@ -0,0 +1,21 @@
+'use strict';
+
+exports = module.exports = {
+    getIp: getIp
+};
+
+var assert = require('assert'),
+    os = require('os'),
+    SysInfoError = require('../sysinfo.js').SysInfoError;
+
+function getIp(callback) {
+    assert.strictEqual(typeof callback, 'function');
+
+    try {
+        var ip = os.networkInterfaces().eth0[0].address;
+        return callback(null, ip);
+    } catch (e) 
+        return callback(new SysInfoError(SysInfoError.INTERNAL_ERROR, e));
+    }
+}
+