The former approach of using `nightly` to grab the latest in-dev PHP version isn't working well now that the `nightly` build is an alias for 8.0 ... and 8.0 isn't resolving composer packages since most haven't tagged anything compatible with it yet.
So switching to `7.4snapshot` allows testing against the next announced PHP version set to release later this year.
* Allows for valet to run under PHP 5.5 as well.
Add checks for php55 to the mix.
* Allows for valet to run under PHP 5.5 as well.
Add checks for php55 to the mix.
* Update .travis.yml
* Update PhpFpm.php
* Add tests for php55