Modifications following previous merge
 * Re-worded a bit CHANGELOG.md
 * Improved README.md file.
 * Added contributors file.
 * Minor styling of code.
Updated message for help flag
Using module constant in Env::Exporter module
 * It seems that using @@ in a module works only inside it and that
   is not possible to use it outside the module afterwards.
Added possibility to change script path in command `vagrant user env`
 * The argument -s, --script-path can be used to specify the location
   where the script path should be located.
Bumped developement to 2.1.0
 * There will be new feature in this release.