@Sean
I think something is not right with the PyPI distribution of rasterio 1.0.14. I did pip install rasterio into a clean virtualenv and it installed rasterio. See the pip show rasterio output:
rio
---
Metadata-Version: 2.1
Name: rasterio
Version: 1.0.14
Summary: Fast and direct raster I/O for use with Numpy and SciPy
Author: Sean Gillies
Installer: pip
License: BSD
Location: /usr/local/lib/python2.7/dist-packages
Requires: cligj, snuggs, click, enum34, attrs, affine, numpy, click-plugins
Classifiers:
Development Status :: 4 - Beta
Intended Audience :: Developers
Intended Audience :: Information Technology
Intended Audience :: Science/Research
License :: OSI Approved :: BSD License
Programming Language :: C
Programming Language :: Cython
Programming Language :: Python :: 2.7
Programming Language :: Python :: 3.3
Programming Language :: Python :: 3.4
....
However, when I look at site-packages at /usr/local/lib/python2.7/dist-packages/rasterio/ and code for path.py session.py there is no GSSession class or no gs:// paths in the remote schemes in path.py. I got around by git pull source from mapbox/rasterio and doing a local pip install -e . and the above code I pasted works. I don't know if something is wrong with PyPI package distribution. I am curious if others have had success with the latest rasterio 1.0.14 and the new features.
pip show rasterio
pip show rasterio