code: function getClient(uri, cb) {
    if(typeof uri === 'function') {
      cb = uri;
      uri = conf.db;
    }
    connect(uri, function(err, client, done) {
      if(err) {
        cb(err, null, done);
      } else {
        cb(null, client, done);
      }
    });
  }
docs: Returns a pg client, you can either specify a connection uri
  or let the function use `conf.db`
  
  ### Example:
  
  ```js
  getClient('tcp://anon@acme.com', function(err, client, done) {});
  ```
  
  ```js
  getClient(function(err, client, done) {});
  ```
  
  @param {*} uri
  @param {Function} cb