Prepare 1.5 release

[fzaninotto]

• Document more than 100 merged PRs in Changelog
• Update composer.json
• Tag release in Git
• Update the Release section in GitHub
• Write a blog post about the changes
• ??????
• Profit

[GrahamCampbell]

Update composer.json

What needs to happen there?

[fzaninotto]

Update the line

        "branch-alias": {
            "dev-master": "1.5.x-dev"

[GrahamCampbell]

Why does that need updating? Are you already sure you're not going to do a 1.5.1 release at any point?

[fzaninotto]

I'm not sure, but I probably won't.