Add mercurial directories to default list of ignored names

atom already ignored git and svn directories. It makes sense to ignore
mercurial (.hg) directories as well.
append .cmd to apm in package-manager.coffee if platform is win32
avoids NOENT error when searching for packages
:memo: Some simple documentation fixes
Upgrade to scrollbar-style@0.4.0
Upgrade to pathwatcher@1.2.4
Merge pull request #2071 from lee-dohm/doc-fix

:memo: Some simple documentation fixes
Merge pull request #2052 from AngelEzquerra/ignore_mercurial_files

Add mercurial directories to default list of ignored names
remove os require use process.platform instead
Upgrade to text-buffer@2.2.1
Upgrade to text-buffer@2.2.2
Avoid problems with version pattern ^X.Y.Z

Older versions of npm don't recognize that pattern
Merge branch 'master' of https://github.com/bradgearon/atom