Move illuminate and symfony dependencies to require-dev

This is only required during development, for end user the Laravel installation
would already the requirement installed, this also prevent error such as
laravel/framework#1524

Signed-off-by: crynobone <crynobone@gmail.com>
Merge pull request #18 from crynobone/patch/composer

Move illuminate and symfony dependencies to require-dev

Prevent error such as laravel/framework#1524