Updated PG dependency to latest version to fix security vulerability

[mattisfrommars]

The PG module used has a "critical" security flaw in and shouldn't be depended on any more

[RWOverdijk]

3 breaking changes equals the need for some serious testing.

[mattisfrommars]

Agreed. Can you help me to get the automated test suite running? I'm getting the following error:

  cli 0.10-rc8
Possibly unhandled Error: Cannot find module 'path/to/sails-migrations/test/fixtures/sample_apps/0.10-rc8/node_modules/sails/package'```

I can't find any documentation on how to get the tests running either. (Once I understand what the issue is I'm happy to help improve the docs)

[RWOverdijk]

I think this repo is just outdated and requires a lot of work to function with the new version.