ipython 5 tab completion not compatible with jpype

New version of ipython probably use threads to implement tab completion that crashes the jvm.

```
import jpype
jpype.startJVM(jpype.get_default_jvm_path())
jpype.java.lang.System.out.<TAB>
```

should not crash the JVM, however it does with ipython 5.

This did not happen with version 4 and with jupyter-console (that uses IPython 5.1.0 in my case).