One Package for Laravel 5.1 and 5.2

Modified the package to detect whether or not the Laravel is version 5.1 or 5.2 and loads the appropriate changes for either one.

• add has-error class to the forms where appropriate
• ServiceProvider loads 5.1 routes directly or 5.2 routes in the "web" route group where needed
• Config file option "auth_routes" attempts to detect if 5.1 version
• master.layout uses config('auth_routes") to generate auth routes (login, logout, register)
• readme updated
• composer updated back to ~5.1 for laravel install level