Feature request: support Laravel 5.1+ (currently 5.5+)

[asgrim]

A friend of mine @liam-wiltshire was asking around for Laravel-focused APMs. I suggested they try out Scout, but they are on an older version of Laravel than we support out the box.

He did a bit of work to get some of the Laravel agent working on Laravel 5.1 and up. See diff - I pulled Liam's changes into a branch in case the fork is deleted: https://github.com/scoutapp/scout-apm-laravel/compare/experimental-laravel-51-support

Investigate bringing these changes into this library and see if we can support earlier Laravel versions.

[asgrim]

Note, pull changes into branch:

git checkout experimental-laravel-51-support
git pull https://github.com/liam-wiltshire/scout-apm-laravel master

[asgrim]

Generally whilst 5.1 was an LTS, it hasn't received security fixes support since 2018. We're probably leaning towards keeping 5.5 (LTS) as the minimum for now, which has security support until Aug 30th 2020. Unless there is increased demand for older Laravel versions, this will probably stay on the "nice to have" list for now.