fix move to EOL behaviour for visual block mode

This fixes a bug where `moveToEol` would truncate the selection according to the current line (we want to move all selections to the end of their respective lines).

## Before
![vim-before](https://cloud.githubusercontent.com/assets/1976582/5516353/34d2856c-884d-11e4-86f3-382eabfb70d2.gif)

## After
![vim-after](https://cloud.githubusercontent.com/assets/1976582/5516355/3761b5c8-884d-11e4-8096-1516a2bf291e.gif)

I've sent a CLA as well -- please let me know if there's anything else you need.

Thanks!