Docker postgres

[masinoa]

This pull request (full details are in the buildmimic/postgres/README.md file):

• provides necessary Dockerfile to run a container with a Postgres server
• bash scripts on the Docker container automatically run the SQL scripts necessary to load the data from
  the csv data files to the Postgres database
• minor changes to the SQL scripts to simplify CSV data loading and reduce error messages by using IF EXISTS clauses

[alistairewj]

Sorry for the delay, have been quite busy on this one! Thanks for the code. Just tried to get it working on Windows and ran into a random assortment of wonderful Windows related errors. Still working through them. Wanted to check though - in the create tables script you omit the backslash in copy statements, i.e. you've written "COPY TABLE_NAME ...." instead of "\COPY TABLE_NAME ...". Is this intentional or a typo? At the moment I've changed it to \COPY.

[masinoa]

@alistairewj Happy to contribute the code. The missing \ in the COPY statement was a typo. Everything ran OK in my tests so I guess I got "lucky" that either Postgres in general or Postgres on Linux was forgiving of this lapse.