Refine data scripts - reduce duplicate creation
Fixes duplicate creation when data scripts are run multiple times.
## Changes in this PR.
The following scripts have been updated to use Django's ``update_or_create`` query:
- [x] get_sites.py
- [x] get_schools.py
- [x] get_users.py
- [x] get_macros.py
- [ ] get_wq_basic.py, get_required_fields.py, get_additional_wq.py, set_tools.py
- [x] get_transects.py
- [x] get_soil.py
- [X] ``School`` field in the WQ model has been changed from ``CharField`` to ``ForeignKey``
- [X] Several CSV column names were simplified
## Testing this PR.
1. Do docker
2. Run get_all.sh twice (Note: script will take a while to run)
3. Check that no duplicates have been made
### Expected Output.
``SELECT COUNT(*) FROM streamwebs_
`` should yield the following number of entries for each table:
* Sites: 242
* Schools: 1398
* Users: 6
* Water Quality: 734
* WQ Samples:
* Macros: 377