Build process to deploy binaries needed for invest-workbench builds

[davemfish]

Please see https://github.com/natcap/invest/pull/194 for the sort of changes we'll need to make to the invest build process to create frozen binaries needed for github.com/natcap/invest-gui. That PR can get re-opened when we're closer to actually needing those changes in a branch on natcap/invest.

Some further improvements to the build process that were suggested by James:

• The binary build step for ubuntu looks pretty similar to the mac binary build step, and that makes me wonder if we'd be able to 1) move the windows build over to conda in order to 2) consolidate all our binary builds into a single configuration.
• The hardcoding of environment paths in our pyinstaller specs (which we've done forever) made me wonder if there were a way to pull the conda environement dynamically, maybe from $CONDA_PREFIX or something?
• Related to the hardcoding of environment paths, I wondered if the gui repo path in pyinstaller.spec could be pulled from the Makefile, something along the lines of make jprint-GIT_GUI_REPO_PATH

[davemfish]

We decided to redesign the workbench build process to be stand-alone and not dependent on pre-built invest binaries. So as of the current state of the workbench build process, we don't need any of the invest changes mentioned in this issue.