Merge pull request #58 from odan/build-status

Fix build status badge

Total issues resolved: **1**

- [37: PHP 8 Support](#37) thanks to @l0gicgate

Add Slim 4 Support

Total issues resolved: **6**

- [12: Removed dependency on Pimple's ServiceProviderInterface and register](#12)
- [13: Remove PHP 5.4 from .travis.yml](#13)
- [14: Use stable version of Slim 3](#14)
- [18: Test with PHP 7.1 but allow build failures](#18)
- [21: Use no-cache header when max-age is zero](#21)
- [23: Force PHPUnit 4.0 for testing](#23)

Merge pull request #9 from dhoffend/must-revalidate

Add must-revalidate flag to Cache-Control

Bump PSR7 version requirement

Version 0.2.0

Version 0.1.0