Solidify plugin installation style

[JustBarnt]

After Review Steps

1. All plugins and core/plugins that have been reviewed will all be considered core plugins.
   Those plugin will be integrated into one file under core called plugins.lua
lua/plugins will then be for users using the distribution, and lua/users/plugins will be obsolete
2. Deprecate user folder. Configuration code will look in the lua folder for a 'user_config.lua' file.
3. Extras will still contain Autocommands and User commands that are not required for the distribution so they can be enabled/disabled