Brackets allows more than one instance on Windows

[JeffryBooher]

Something obviously was broken. We used to check for another running instance and activate that on startup. That doesn't appear to be happening anymore.

1. launch release 42
2. launch it again
   => 2 brackets app windows (probably looking at the same project)

[RaymondLim]

I can reproduce it with sprint 26 build. So I don't think we ever check for another running instance on Windows.

[marcelgerber]

@JeffryBooher @RaymondLim Well, it works for me (downloaded Release 0.42, Hacking Enabled, Windows 8.1 Update 1)

I'm starting Brackets via Win8's Metro/ModernUI, if that matters.

[JeffryBooher]

@RaymondLim we added that with this pr adobe/brackets-shell#296

[JeffryBooher]

@SAplayer Yep, that happens for me too on Win 8.1 but when you launch from Windows Explorer, it opens a second instance.

[JeffryBooher]

Closing as this only works when a file is opened from the command line.