Format menu shortcuts for the Mac

Also update the X/C/V dialog to use say Command for Mac.

Before: 

![screen shot 2013-11-06 at 9 02 33 am](https://f.cloud.github.com/assets/2660251/1482935/b82d8bca-46ed-11e3-95b6-fdec97354dd3.png)

![screen shot 2013-11-06 at 9 02 55 am](https://f.cloud.github.com/assets/2660251/1482940/cf333ce8-46ed-11e3-9c62-170e10ceff65.png)

After:

![screen shot 2013-11-06 at 9 04 12 am](https://f.cloud.github.com/assets/2660251/1482938/c451f828-46ed-11e3-828c-072d3f6ae7f2.png)

![screen shot 2013-11-06 at 9 04 27 am](https://f.cloud.github.com/assets/2660251/1482943/d3fd8e0e-46ed-11e3-8d6b-c70eb64be0b3.png)