Unzip plugin zip file in loadPluginFromPath()

[janhoy]

This is an attempt for auto unzip on load, so UpdateManager can install and update without problems. Was this the approach you had in mind?

Fixes #132

[coveralls]

Coverage increased (+2.3%) to 27.693% when pulling 2df3827 on cominvent:unzip-on-load into c9f98de on decebals:master.

[decebals]

The code looks good with one observation on my part.
The part with plugin packed as a zip file and the unpack process before plugin loading, is available in Default implementation (DefaultPluginManager, DefaultRepository, ...), the AbstractPluginManager knows nothing about this aspect. From this reason I think that it's a good idea to move the expand zip line from AbstractPluginManager.loadPluginFromPath to DefaultPluginManager.loadPluginFromPath.

// pseudo code
public class DefaultPluginManager extends AbstractPluginManager {
 
    ... other methods

    Override
    protected PluginWrapper loadPluginFromPath(Path pluginPath) throws PluginException {
        // first unzip any ZIP files
        try {
            pluginPath = FileUtils.expandIfZip(pluginPath);
        } catch (Exception e) {
            log.warn("Failed to unzip " + pluginPath, e);
            return null;
        }

        return super.loadPluginFromPath(pluginPath); // where pluginPath is the value returned by expandIfZip
    }

}

Did what I said make sense to you?

[coveralls]

Coverage increased (+2.2%) to 27.632% when pulling 8aa91a3 on cominvent:unzip-on-load into c9f98de on decebals:master.

[decebals]

Excellent. Thanks!