Workaround mangled javadocs

The current build fails when executing <tt>gradle install</tt> with the following message:

    100 errors
    100 warnings
    :javadoc <span color="yellow">FAILED</span>
    
    <span color="red">FAILURE: Build failed with an exception.</span>
    
    * What went wrong:
    Execution failed for task ':javadoc'.

In my opinion, the javadocs are too mangled to try to fix them. This workaround allows the build to ignore javadoc errors when installing artifacts.