.osx: Change minimize/maximize window effect

By default, Mac OS X Mavericks, uses the annoying `genie` effect whenever windows are minimized/maximized. 

This commit changes that preference and makes OS X use the more tolerable `scale` effect.

Related issue: #270

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* `genie` effect:

<img src="https://f.cloud.github.com/assets/1223565/2344097/50332d14-a51a-11e3-8f1c-9883b88f4dd8.gif" width="610px" height="440px">

* `scale` effect:

<img src="https://f.cloud.github.com/assets/1223565/2344101/7dbcdd84-a51a-11e3-9874-313333fa544b.gif" width="610px" height="440px">