Fixed issue #330(cycle in code when rendering anonymous individual in Manchester OWL syntax)

I just replaced the call of toString() with toStringID() such that the node ID is used according to specification http://www.w3.org/TR/owl2-manchester-syntax/ 

```
individual ::= individualIRI | nodeID
individualIRI ::= IRI
nodeID := a finite sequence of characters matching the BLANK_NODE_LABEL production of [SPARQL]
```

Not sure if the cycle occurs in some other syntax styles too. This should be checked seriously.

Creating a JUnit test seems to bit a little bit tricky because several Maven modules are needed (parsers, impl, api).