Improve .gitignore

[tkissing]

Add common IDE folder names, MacOS X system files/folders like .Trashes or .DS_STORE etc

This prevents accidental commits of files that should not be under version control without putting the burden on potential contributors

[konobi]

I like it, what's the default set that we want to support as a minimum?

[tkissing]

There is a lot at https://github.com/github/gitignore
I'd consider these essential:

https://github.com/github/gitignore/blob/master/Node.gitignore
https://github.com/github/gitignore/blob/master/Global/Archives.gitignore
https://github.com/github/gitignore/blob/master/Global/OSX.gitignore
https://github.com/github/gitignore/blob/master/Global/Windows.gitignore

Any editor-specific ones from the Global folder are a plus I guess.

From a how-to-do-it perspective it's probably best if kwalitee can take a list of filenames or URLs of "desired" .gitignore contents and then compare them. A "kwalitee badge" on the npm might require only those 4 above, but I might want to run kwalitee locally and require 3 additional ones.

[konobi]

I think we'd want that list of file patterns to be the same everywhere, since the package can be unbundled anywhere.