Add postgres as a conda dependency

[sdc50]

I propose that we add postgres as a conda dependency and add CLI endpoints for initializing and starting the database. This has the following benefits:

 * Docker becomes optional when installing Tethys

 * It reinforces the idea that the Tethys database is separate from the app databases

 * It shifts the paradigm of Docker containers from being part of the "Tethys stack" to being optional resources for apps that are set up as needed. I think this paradigm shift is needed as we potentially add to the list of Docker containers that we offer (e.g. ArcServer, QGIS server, CKAN, etc.).

 * Enables Tethys to be packaged and installed through Miniconda.

I envision this getting to the point that if someone who wants to develop a Tethys app using the latest release of Tethys it would be as easy as installing Miniconda, and then something like:

conda install tethys
tethys initdb
tethys scaffold myapp
cd tethysapp-myapp
python setup.py develop
tethys start

This would install the latest packaged Tethys from the conda-forge package repository, initialize the database, and then after setting up the app, start the tethys server. 

Other considerations:

For this setup to be fully functional then we would need to implement the planned app settings and allow database servers to be registered in Tethys the same way that Geoserver, or CKAN are. Until then, we are not really separating the Tethys database from the app database, we are just moving it to the conda environment instead of a Docker. Also, spatial persistent stores would not be supported unless the postgis Docker container were installed.

If we are interested in moving this direction then could add the dependency and the CLI tools as an alternative way to install Tethys for now. Once app settings is fully implemented giving us the ability to assign database servers to apps, then we can make this the default installation for development environments.

[swainn]

+1

[misssc...@gmail.com]

Hvv