3.0 - Add plugin shell.

It symlinks / copies plugin's assets to app's webroot. Thought this might be handy to use in deployment tasks.

One issue I am having is with plugins with vendor namespace. The task first creates directory for vendor name and then proceeds to create symlink for the plugin's webroot inside it, but it fails resulting in folder being copied instead. 

If the directory for vendor name exists beforehand the symlink is created without problem. So for some reason php doesn't seem to realize the directory exists when it's created by the script itself. Using clearstatcache() doesn't help.
Sorry I edited my comment a couple of times after first posting.

Being able to process only all plugins is a bit of a handicap IMO - just because a plugin is in use doesn't necessarily mean the webroot files are; hence being able to process _one_ or _this list of_ plugins is something I think should be accounted for.

I've used [a similar shell](https://github.com/nodesagency/Platform-Common-Plugin/blob/develop/Console/Command/SymlinkAssetsShell.php) in the past and one of the things it did which was _extremely useful_ was to correct existing, bad files/links. Nowadays everyone should be using VCS, so if they accidentally delete something from their application webroot I don't see that as a big deal - whereas leaving an app in a potentially stale state is.