Add command for making input type

[killtw]

Usage:

$ php artisan make:graphql:input <input name>

[coveralls]

Coverage increased (+0.6%) to 71.088% when pulling 5a4896f on killtw:make_input into 37e9383 on Folkloreatelier:develop.

[mohammad-fouladgar]

i had already the same pull request in PR #298