start.sh fails on recent osx

[maxandersen]

not sure what the fix is but when running start.sh on brand new MacBook you end up with:

Extracting pycparser-2.19-py2.7.egg to /private/tmp/easy_install-ZFRIOS/cryptography-2.7/.eggs

Installed /private/tmp/easy_install-ZFRIOS/cryptography-2.7/.eggs/pycparser-2.19-py2.7.egg
/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/dist.py:267: UserWarning: Unknown distribution option: 'python_requires'
  warnings.warn(msg)
/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/dist.py:267: UserWarning: Unknown distribution option: 'long_description_content_type'
  warnings.warn(msg)
no previously-included directories found matching 'docs/_build'
warning: no previously-included files found matching 'vectors'
warning: no previously-included files matching '*' found under directory 'vectors'
warning: no previously-included files found matching 'azure-pipelines.yml'
warning: no previously-included files found matching '.azure-pipelines'
warning: no previously-included files found matching '.travis.yml'
warning: no previously-included files found matching '.travis'
warning: no previously-included files matching '*' found under directory '.azure-pipelines'
warning: no previously-included files matching '*' found under directory '.travis'
warning: no previously-included files found matching 'release.py'
warning: no previously-included files found matching '.coveragerc'
warning: no previously-included files found matching 'codecov.yml'
warning: no previously-included files found matching 'dev-requirements.txt'
warning: no previously-included files found matching 'rtd-requirements.txt'
warning: no previously-included files found matching 'tox.ini'
build/temp.macosx-10.14-intel-2.7/_openssl.c:498:10: fatal error: 'openssl/opensslv.h' file not found
#include <openssl/opensslv.h>
         ^~~~~~~~~~~~~~~~~~~~