Upgrade to electron 0.30.5

[kangas]

Bump electron version to latest 0.30 version which is 0.30.5. This resolves some ASAR problems I encountered on Windows.

I don't want to use 0.31.0 yet: it upgrades io.js and thus breaks native modules.

[kangas]

Testing on OS X: "npm run release" builds an app, connection panel works normally, but the primary window (after connection selected) is blank. :(

I see the following (possibly unrelated):

Mon, 24 Aug 2015 22:15:46 GMT scout-electron:window-manager creating new window
Mon, 24 Aug 2015 22:15:46 GMT scout-electron:menu attaching window menu
[51752:0824/181546:INFO:CONSOLE(124)] "It is not allowed to open new window from this WebContents", source: /Users/kangas/workspace/scout/dist/MongoDB Scout-darwin-x64/MongoDB Scout.app/Contents/Resources/atom.asar/renderer/lib/override.js (124)