Support for include

[imikemiller]

Added support to pass an include script as first argument to the tinker command. Allows usage like this

php artisan tinker path/to/tinker/script.php

script.php

$environment = app()->environment();
$output = new Symfony\Component\Console\Output\ConsoleOutput();
$output->writeln("<info>Hello the app environment is `{$environment}`</info>");
$output->writeln("<comment>Did something</comment>");
$output->writeln("<error>Did something bad</error>");

[joelhy]

@imikemiller Would you please update tinker command usage in README.md?