Cannot maintain a pool with 1 connection that is allowed to idle

[geertweening]

When trying to create a pool with the following options I expect to have 1 object available at all times and the object not to be destroyed when it times out.

options {
  "refreshIdle": false,
  "min": 1,
  "max": 1
}

Instead the object is destroyed when the timeout is hit. This happens since the Pool constructor will assume the min should always be at least 1 less than the max. The options above end up resulting in a max of 1 and a min of 0

A simple solution could be to remove the max-1 assumption for the min value.

[geertweening]

@tgriesser @coopernurse any thoughts on this?