fix(composer): Always open new composer windows from the main window so that AccountStore.current() is correct

Fixes T3479

src/atom.coffee

@@ -202,7 +202,7 @@ class Atom extends Model
       # up into the browser process. This prevents us from needing this crap, which has to be
       # updated every time a new application: command is added:
       # https://github.com/atom/atom/blob/master/src/workspace-element.coffee#L119
-      if event.binding.command.indexOf('application:') is 0 and event.binding.selector is "body"
+      if event.binding.command.indexOf('application:') is 0 and event.binding.selector.indexOf("body") is 0
         ipc.send('command', event.binding.command)
 
     unless @inSpecMode()

src/browser/application.coffee

@@ -254,6 +254,7 @@ class Application
       atomWindow ?= @windowManager.focusedWindow()
       atomWindow?.browserWindow.inspectElement(x, y)
 
+    @on 'application:new-message', => @windowManager.sendToMainWindow('new-message')
     @on 'application:send-feedback', => @windowManager.sendToMainWindow('send-feedback')
     @on 'application:open-preferences', => @windowManager.sendToMainWindow('open-preferences')
     @on 'application:show-main-window', => @openWindowsForTokenState()

src/flux/stores/draft-store.coffee

@@ -55,8 +55,8 @@ class DraftStore
     @listenTo Actions.composeNewBlankDraft, @_onPopoutBlankDraft
     @listenTo Actions.draftSendingFailed, @_onDraftSendingFailed
 
-    atom.commands.add 'body',
-      'application:new-message': => @_onPopoutBlankDraft()
+    if atom.isMainWindow()
+      ipc.on 'new-message', => @_onPopoutBlankDraft()
 
     # Remember that these two actions only fire in the current window and
     # are picked up by the instance of the DraftStore in the current
@@ -92,7 +92,6 @@ class DraftStore
 
     ipc.on 'mailto', @_onHandleMailtoLink
 
-
     ipc.on 'inline-styles-result', @_onInlineStylesResult
 
     # TODO: Doesn't work if we do window.addEventListener, but this is