Enhancement: SilverStripe 4 compatibility

[robbieaverill]

This is a placeholder issue for SS4 compatibility.

Pre-requisites

• Branch current master off to 1 or similar for maintaining the current version
• Update/add composer branch alias to 2.0.x-dev

Requirements

• Add namespacing for module including upgrader mapping file
• PSR-2 code formatting (looks like its mostly done)
• Implement core namespaces, update configuration (including CI builds), tests and template locations
• Add PSR-4 autoloader (inc. move code/ to src/ for consistency)
• Update documentation

Implications

• Minimum PHP version becomes 5.5

[robbieaverill]

@dljoseph if you wouldn't mind doing the branching and update the composer alias, I'm happy to make PRs for the rest of the changes required.

"extra": {
    "branch-alias": {
        "dev-master": "2.0.x-dev"
    }
}

[dljoseph]

Hi Robbie, Thanks for this. Sorry I'm a bit late in responding. I'll do that today.

[dljoseph]

Hi @robbieaverill that's done. Branch 1.0 created for maintaining compatible SilverStripe 3.x version, composer.json branch-alias added to master branch for SilverStripe 4.x. Go ahead and submit your PRs.