Init row

Allow customizing of the initial row for more flexible layout options. This also fixes a small bug w/ the positioning of even rows when spacing is provided.

Spacing issue before:

![screen shot 2014-11-03 at 9 50 22 pm](https://cloud.githubusercontent.com/assets/22249/4895292/8f944f8e-63e6-11e4-812e-a61cfb7082e6.png)

Spacing issue after:

![screen shot 2014-11-03 at 9 51 42 pm](https://cloud.githubusercontent.com/assets/22249/4895293/b2e2d85c-63e6-11e4-81cd-0e896e439792.png)

w/o initRow:

![screen shot 2014-11-03 at 9 52 33 pm](https://cloud.githubusercontent.com/assets/22249/4895301/e1b4b5c4-63e6-11e4-9843-a8516eff1048.png)

w/ initRow:

![screen shot 2014-11-03 at 9 52 57 pm](https://cloud.githubusercontent.com/assets/22249/4895304/ec536336-63e6-11e4-867c-d6a568d444d8.png)