This pull request combined all the patches / threads i could find for making build on windows work.

Just added the PR incase its any help getting the changes in.
It wonder if handling normalized paths could be pushed to `pake`.  We already have places below where we rely on things like [`ifind('src/ol')`](https://github.com/s-innovations/ol3/blob/6bc67531ce18dc053f92d5d242c52bacf512798c/build.py#L144) or [`if path != 'examples/jquery.min.js'`](https://github.com/s-innovations/ol3/blob/6bc67531ce18dc053f92d5d242c52bacf512798c/build.py#L115).  It would be nice not to have to guess where one form works and the other doesn't.

cc @openlayers/team-openlayers