Allow developer to change the environment to run Tinker under (equivalent to --env option in command line)

[aokrasavin]

At present, when running the plugin, it always runs under default environment. It would be useful to allow use to select an environment for each console.
Concrete example - I have a code which runs perfectly well in production, but fails during testing (which obviously runs under --dev=testing). This was ultimately traced to issues in configurations.

[Roboroads]

You can change the environment variables in your PHP Interpreter settings :)