Fix for issue #33, parse MongoDB URL with multiple nodes

[kierandarcy]

No description provided.

[singingwolfboy]

This looks rather complicated. I'm not familiar with mongodb connection URLs. Can you give me a concrete example of a connection URL that Flask-Heroku is currently failing to parse?

[kierandarcy]

Thank you for taking the time to look at this. This is an example of an actual URL which Flask-Heroku is currently failing to parse.

mongodb://username:password@ds012345-a0.mlab.com:12345,ds012345-a1.mlab.com:12345/database?replicaSet=rs-ds012345

(Python's builtin urlparse will fail when trying to parse the port in this URL.)