Remove calls to code.inf.unibz.it

[agrabovskis]

The site seems to be not available. There are 2 features related to the site:

• Version update check (which can be done by Eclipse)
• Issue reporting

Removing those two features allowed to remove dependency to org.apache.commons.httpclient and org.eclipse.core.net bundles.

[ajermakovics]

Hi @agrabovskis

Thank you very much! Would be keen to merge this.
At the moment there seem to be some build errors on Travis CI.

[agrabovskis]

Yes, I noticed the build issues and will address them. The issue is caused by using newer Java/Eclipse combination. Since I'm also working on updating the plugin to work with Eclipse Photon (the changes are huge - updating from Lucene 2.9+ to 7.1+), I'm not entirely sure should I revert the changes or simply update the minimum required Java/Eclipse version.