This patch simplifies the manual development environment setup
documentation by omiting setup for pyenv or virtualenvwrapper. They are
both very good environment management tools, but they don't play nice
with each other.
The updated instructions use the virtualenv package directly, and use
the more straight-forward barbican-api script instead of barbican.sh
Change-Id: Idf9717f18e3599839a5bf8b983b47b7802b9187c
e2413b0fc6