pass pip --build $BUILDDIR option

to build on <temporal> folder, otherwise, on virtualenv pip builds
in ./build, which might be slow.
Merge branch 'master' into build-tweaks
Merge branch 'master' into build-tweaks
Merge pull request #204 from breznak/build-tweaks

pass pip --build $BUILDDIR option
Merge remote-tracking branch 'upstream/master'