one composer package support multiple laravel versions

[sinkcup]

because of different laravel versions have different dependencies, I use different branches to support:

• laravel-5-5: bootstrap 3.3, socialite 3.3
• laravel-5-6: bootstrap 4.0, socialite 3.3
• master(laravel 5.7): bootstrap 4.0, socialite 4.1

it's difficult to maintain.

actually, there are a few different files:

• views
• composer.json

so, maybe I should use one composer package to support multiple laravel versions.