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.
> …and mod_rewrite rules?

What about them?

> Maybe a confirmation is required in case symlinks failed? (symlinks are not supported, would you like to copy the assets?)

That's an option though there should be a non interactive mode too which copies by default for usage in deployment scripts.

> Additionally if assets are copied, maybe add a sync feature, to update assets and remove old assets?

Run the shell again and the files will be updated. PHP's `copy()` overwrites files.