Duplicate file behavior -> Open new file automatically

![gifrecord_2014-06-14_213447](https://cloud.githubusercontent.com/assets/5219415/3279421/12c83624-f3fb-11e3-8863-665f8bd9d330.gif)

* Open the newly duplicated file in the workspace and focus it.
* Set the cursor to the most recent selector if we duplicated the formerly focused file.

Closes #101.

I updated temp to `~0.7.0` to allow the specs to pass and adjusted the existing tests for the new behavior. At the moment temp.clean() is not called after the very last spec so it leaves back 1 folder in the /tmp folder. Don't know if we can fix that, I didn't feel like it was very important.

I also removed a seemingly useless `directoryPath = path.dirname(newPath)` line, specs didn't care so I think its all right. (_Did you know that fs-plus.copySync() will fail horribly if one is trying to copy a single file with it? Shouldnt it be called copyDirSync() instead? Or do you want me to open an issue over there?_)
Since we're using a `try...catch` anyways we could do without checking for `if not error` right?