Fix double escaping graphml

[vga91]

The javax.xml.stream.XMLStreamWriter escape some chars, e.g from & to &, so we cannot use StringEscapeUtils.escapeXml10() because we would escape twice. We just have to remove the invalid xml chars.

The bug is occurred here, and not in 4.4, because of different retrieving order of node.getPropertyKeys(). Therefore, I added more chars in test cases.

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Also, added missing @Test in testExportGraphGraphMLQueryTinkerPop

[gem-neo4j]

Looks good, out of curiosity, where did you get the list for the invalid characters? are we sure that contains all of them? :)

[vga91]

I've extracted the char list from the previous implementation, StringEscapeUtils.escapeXml10.

Alternatively we could change the pattern in a negative way, to ^[setOfAllowedChars], like here. However, the results match each other.