Consider adding "bootstrap-X.Y.Z/" to the zip path of the dist downloads

Created by: zoowar

Consider adding "bootstrap-x.y.a/" to the zip path so that files unzip into a versioned bootstrap directory.

Currently, the zip file unzips into "dist/" regardless of which version is unzipped in the current directory. I would be nice if the bootstrap-3.3.1-dist.zip unzipped into "bootstrap-3.3.1/dist/".