Fix usage for Node 6 and Sails 0.12

[joaosa]

When using this with Node 6.1.0, I started getting:

sails-migrations "status"
.../node_modules undefined
path.js:7
    throw new TypeError('Path must be a string. Received ' + inspect(path));
    ^
TypeError: Path must be a string. Received undefined
    at assertPath (path.js:7:11)
    at Object.join (path.js:1211:7)
    at Function.SailsIntegration.getSailsConfig...

Updating liftoff did the trick.

While I was at it, I also noticed the configs for Sails 0.12 weren't being picked up properly. So I fixed that as well :)

Finally, there was a password authentication issue on node-postgres caused by Node 6. Taking knex/knex#1372 as a reference, I upgraded its version to 4.5.5, thus fixing the issue.