Label consistency

[plehegar]

From @tobie :
It would be nice to have a bit more consistency (sometimes you're using ":" as a namespace, sometimes, using spaces, sometimes dashes). I'd also recommend avoiding whitespace, which makes searching more complicated (you have to quote labels) and URLs less user friendly (%20 everywhere), but that's a minor issue.

[tripu]

+1 to all-lowercase-and-using-dashes, for consistency.