Trying to get tests to run without external run_tests script; no luck.  Test environment is not installing with dependencies.

Because tests will be run after model_server is installed as a package, they revert to importing model_server.base.*

Merged in usage of session module global object instead of singleton class; still working through tests

# Conflicts:
#	model_server/base/api.py
#	model_server/extensions/ilastik/router.py

Resolved Session re-initialization issue: Singleton.__call__() recognizes existing instances relative to namespace (model_server.base.session vs. base.session)