More robust parsing of mongodb connection string. Use new url parser.

[sagannotcarl]

When using a more complex mongo connection string the current mongodb connection template throws and error trying to get the database name.

In my case I am connecting to compose.io using the database string:
mongodb://[username]:[password]@aws-us-east-1-portal.20.dblayer.com:21660,aws-us-east-1-portal.21.dblayer.com:21660/compose?authSource=admin&ssl=true

And my app would fail to start with the following error:
MongoError: database names cannot contain the character '.'.

So I am using the parseConnectionString function from mongodb-core to get the database name instead of url.parse, since that can't handle the mongodb failover syntax. I pass in an empty function as the callback since MongoClient.connect() will already throw an error if the mongo connection string is not formatted correctly.

I was also getting a DeprecationWarning which was fixed for mongoose here cf613ef, so I applied the same fix to the mongodb template.

[daffl]

Thank you. Wouldn't this also need mongodb-core added as a dependency?

[sagannotcarl]

Yes it would. Sorry I don't have a good enough understanding of the generators, I assumed that since this was in the mongodb template mongodb-core could be assumed.

If that's not the case could you recommend the best way to make mongodb-core a dependency and I'll add it.

Thanks for the feedback!

[sagannotcarl]

@daffl I added the mongodb-core dependency in generators/connection/index.js.

Anything else you can see here you'd like me to change?