runner watcher fires when editing (but not saving) files in vim

[glasser]

Breaking this out from #3285 (comment) because we are not blocking the release on it.

@robfallows:

I'm seeing lots of client refreshes when opening and editing css files (i.e. before saving changes). It seems to "see" the vim .name.swp file as something to track (this may have been in previous releases - I've only just noticed it).

Otherwise, the speed of refresh, particularly on server code is way better than 1.0.1 - It's taking about 1/10 the time it used to. Nice work!

@glasser:

@robfallows Can you provide more detailed instructions on how to reproduce this? Can you reproduce this in, eg, a brand new meteor created app? What file are you editing in what directory? What OS are you on? I can't reproduce this with editing (and not saving) the CSS file in the default meteor created app on OSX.
@robfallows I can reproduce this with editing files in the public directory, but that does not appear to be a regression vs 1.0.1. (In the public directory we rebuild on ANY file change except those in bundler.ignoreFiles, and I guess we don't have an ignore regexp for vim backup files. But in the normal source directories we only watch for files of known source code extensions.

So I can't reproduce the precise thing reported, but I can reproduce it in public and it's probably worth updating bundler.ignoreFiles.