Add basic connect

Fixes #5 
The advantage of using flexible version numbers is the user gets the dependency only installed once, even if he depends not on the exact same version.
As we are providing a mongodb library this probably does’t matter. I can’t imagine that someone will browserify that to run in the browser.

BTW: The `^` pattern has changed in npm 2.0 so versions below 1.0 will be only updated by the minor version number.