Minor changes, no BC breaks

I changed the PHP requirement from >7.1 to >=7.1 to also allow older PHP version to use the library.

Also I added a CHANGELOG.md.

Initial release 1.0

The initial release of this small component :) Super easy to use (with default parameters) via:

use \lfischer\internet\Internet;

$available = Internet::available();

Or with more options regarding host, port, options, timeout and optional logging (via PSR-3)

use \lfischer\internet\Internet;

// Check the availability by connecting to Google on port 80.
$available = (new Internet('www.google.com', 80))->check();

For further information take a look at the README :)