Plugin addons for spot bugs being copied to 'target' unnecessarily

[hazendaz]

The processing of this plugin copies a lot of files used during the spotbugs check to the target directory. Of this, any plugin addons are copied into that space. This was originally raised as issue #34 and fixed via #238. However, that caused other negative side effects. The original patch was reverted and subsequent patch added that better handles windows thus the original deeply nested artifact. However there is still a point that the artifacts probably shouldn't be copied as those are very unlikely to change given they run off final versions so its just wasting resources. Look at that in more detail for better way to handle and potentially just getting out rather than attempting to perform a copy in this area.

[gusega]

we had an issue because of this in our project, as we are producing a single jar artifact in the target folder and our deployment scripts were searching for the jar. The workaround was to add the configuration property
<xmlOutputDirectory>${project.build.directory}/spotbugs-results</xmlOutputDirectory>. This way the plugin.jar gets copied into the spotbugs-results subdirectory of target and our deployment scripts worked fine.

[hazendaz]

@gusega Like that idea to at least fix up the project a bit. I know its been a while but if you would be willing to raise a PR for making that the normal process, that is something that I could get merged into code base for future release. Otherwise I'll try to look into this more at some future date.