Implement autoupdate/automigrate

The implementation forks a new node process to execute the method in the context of the target project.

Close #106.

/to @ritch please review
/cc @seanbrookes @altsang 

@rmg The tests require a local MySQL database to be configured for the tests - see `bin/setup-mysql`. What is needed to get such setup on CI build slaves? Shall I disable those tests on Jenkins for the time being?
This output is already wrapped in a debug log - see  `models/data-source-definition.js`

```
+      debug(
+        '--invoke stdout--\n%s--invoke stderr--\n%s--invoke end--',
+        stdout, stderr);
```