[#813] Recreated branch from develop

Reverted to not merge with future/rsr_v3 but base
on develop.
[#813] Fixed bugs that full dataset revealed

- added pg_alts.py a script that alters to the column
  types Django expects from Postgres.
- fixed flaky asserts by using other module load routine
- renamed validate_postgres.py to pg_tests.py
- created migration script
[#813] Fixed bug in pg_migrate.sh

Since we switch user the password env variable was not carried
though.
Update pg_readme.md
[#813] Fixed readme
[#813] Added a tab for better readability
[#813] Pipe to log
[#813] Updated instructions to use sudo
Merge branch 'develop' into feature/813_postgres_v2
[#813] Merge branch 'develop' into feature/813_postgres_v2
Merge pull request #961 from akvo/feature/813_postgres_v2

[#813] Switch V2 to PostgreSQL