Anything using theses exported variables should be using them in the new
context rather than the old

PROFILE_PATH and WEBCONCURRENCY_PROFILE_PATH must land in the new build context and
so should be set after the new context is created

using the apt buildpack in combination with the multi buildpack exports some
paths out of ORIG_BUILD_DIR. By copying instead of moving this should allow
building of python modules that have dependancies on any packages installed
into ORIG_BUILD_DIR.

Revert "Update Readme.md"

Update Readme.md

Update pip to 7.1.0

Set xtrace if $BUILDPACK_XTRACE set

Update pip to v7.0.3 and setuptools to v17.0

fixes #231

For debugging or for folks who are curious about how the buildpack
works.