composer.lock should not be in .gitignore

[cmmarslender]

composer.lock file should be committed to our projects so that when we deploy them, we can run composer install and get a very specific set of package versions installed.

I could see maybe not wanting a composer.lock file in the scaffold repo, but we definitely want it in the repos that are generated as part of the scaffolding.

[dana-ross]

It's a holdover from WP Make's templates. I agree it should be removed and we'll just make a point not to add it to the scaffold's repo /cc @timwright12

[dana-ross]

Addressed in e2d3616