Add test for key only entry

[koppor]

This adds a test case showing that a bibtex entry having a key only raises an exception. IMHO following entry is valid bibtex:

@article{test,
}

The entry just hasn't any fields.

[vruusmann]

@koppor Are there any other high-priority issues?

[koppor]

Thank you for asking. It was the only one I encountered while preparing CloudRef for a release.

[vruusmann]

I've pushed JBibTeX version 1.0.17 to the Maven Central repository, which includes this fix.

[koppor]

We successfully released version 0.1.0 of CloudRef: https://github.com/JabRef/cloudref/releases/tag/0.1.0

Thank you for the quick action taken!

[koppor]

I don't know, why travis builds. Here, the test of parseBibTex() fails, because the entry "first" is not in the list.

[vruusmann]

The JBibTeX project builds on my computer, and on Travis CI - perhaps there's something wrong with computer/setup.

You could start with a clean checkout. And if that also fails, tell me more about your Architecture/OS/Java.