Add a colon after the 'Tab Size' and 'Spaces' in the status bar

![spaces](http://f.cl.ly/items/1M3p182b1j0Y1i2U2M2t/Screen%20Shot%202013-08-27%20at%204.53.16%20PM.png "spaces")

This is an improvement over the current, ungrammatical "Spaces 4".