Reenable the analysis of the JSON plugin

[obfischer]

Since the release of jQAssistant 1.3.0 - which contains now also the JSON plugin - the next version of this plugin is scanned by this release. Currently the scan of this plugin fails always as jQAssistant also scans out test JSON documents and fails because of a bug in version 1.3 of the JSON plugin.

Therefore we disable the jQAssistant plugin. But it must be enabled again if we are able to exclude our test documents from the scan. This requires that issue #6 has been solved.

[obfischer]

Should be reenabled with the first release candidate of 1.6.0.