Deprecated functions

[billgeo]

Fixes: #248 Add new line for each issue that was fixed

Change Description:

Fixes deprecated function names since PostGIS 2.1, i.e. ST_Force_2D is now called ST_Force2D ...

Notes for Testing:

1. Start docker shell (db image) from Master
2. su postgres
3. Test that the function fails psql -d gazetteer -c "BEGIN; SELECT gazetteer.gaz_update_export_database(); ROLLBACK;"
4. Clone the repo git clone https://github.com/linz/gazetteer.git
5. Checkout the PR: gh pr checkout 252
6. Apply patch: psql -d gazetteer -f gazetteer/src/sql/gazetteer_export_func.sql
7. Test again: psql -d gazetteer -c "BEGIN; SELECT gazetteer.gaz_update_export_database(); ROLLBACK;"

...

Source Code Documentation Tasks:

• [x] README updated (where applicable)
• [x] CHANGELOG updated

User Documentation Tasks:

• [x] Confluence user guide updated (where applicable)

Testing Tasks:

• [x] Added tests that fail without this change
• [x] All tests are passing in development environment
• [x] Reviewers assigned

Pull Request Management:

• [x] Linked to sub-task
• [x] Linked to the epic

[billgeo]

Thanks @SPlanzer