Additions to the workflow

Hi, I found this workflow very useful and have added a couple of enhancements to it:

- 'krome' launches the currently opened FF tab in Chrome (the reverse of what the original workflow did)

- 'incognito' opens the currently open Chrome tab in a new Incognito Chrome window (this is also bound to Command+Shift+M).

I've also updated the documentation and the screenshot to reflect the new features.

![screenshot_workflow](https://f.cloud.github.com/assets/238128/522200/99582af2-c006-11e2-90c2-3d7dd0f1cddf.png)

I'd appreciate if you could include them into the original.