Reorganize file structure

[camirmas]

Changes

CI Updates

This update makes CI builds consistent with the install instructions for developers. It also allows us to set up Mac builds, which are disabled for now (see #154).

Structural Changes

This is essentially a small chunk of the work happening in dev/refactor. It creates a new folder structure that has the following high-level structure:

- examples
- hopp
  - add_custom_modules
  - simulation
    - financial
    - layout
    - resource
    - sites
    - technologies
      - dispatch
      - hydrogen
      - pySSC_daotk
      - battery.py
      - clustering.py
      - csp_plant.py
      - detailed_pv_plant.py
      - grid.py
      - power_source.py
      - pv_plant.py
      - tower_plant.py
      - trough_plant.py
      - wind_plant.py
    - hybrid_simulation.py
    - reopt.py
    - utility_rate.py
  - utils
    - keys
    - log
- resource_files 
- tests
  - analysis
  - hopp
- tools
...

This is part of a proposed strategy to make small, manageable PRs into develop (now branch-protected) based on the refactor work, which will allow us to stay up-to-date with master, keep the test suite stable, and review the software design in reasonable chunks. dev/refactor in its current state has diverged greatly from master (see compare, which is so large that GitHub can't display the file changes), and even if we are able to make the CI stable again (current builds fail for an unknown reason), the PR to master will be so large that it will be very difficult to review.

The proposed process is iterative:

1. cherry-pick a single feature or refactor from dev/refactor
2. ensure proper test coverage and stable CI runs
3. PR into develop

For example, the PR after this would pull the HOPP interface changes and yaml input structure, and the PR after that would pull new hydrogen features introduced in Green Steel, etc. in smaller chunks

[camirmas]

Build passing here. Tests will not pass on forked PRs due to NREL_API_KEY security (see #152 for more info)

[camirmas]

Closing this for the moment. Tests are running on #153 so I'm going to see if we can get them fixed and then merged back into dev/refactor