Populate .gitignore with more files

Shouldn't `composer.lock` and `logs` be on `.gitignore`?

Also, previous versions of CakePHP had the "IDE" and "OS" parts which I pasted here (adding `*.sublime-*` for sublime dotfiles).
Fixed in 9509d503eacc7d7e33d36d7b1c1ae02388ea7c9e