#76968164 set width block should have inline text field

Dashboard PR at https://github.com/code-dot-org/dashboard/pull/1205

Instead of having set width have a purple block attached, use an inline text field

Before:
![image](https://cloud.githubusercontent.com/assets/1767466/3927279/72b7b55e-23f9-11e4-9431-237cea798293.png)
after:
![image](https://cloud.githubusercontent.com/assets/1767466/3927282/79da3a64-23f9-11e4-886a-3cdc896fd975.png)