Incompatible is less serious. (1.4.1)

Ensure that the message regarding incompatible nodes is explicitly
clear and doesn't trigger errors.

This is necessary because even in a pure 1.4.1 cluster, depending on
how nodes are started capability negotation might take a few seconds,
where some nodes will be shown as incompatible.

![Clarification](http://cl.ly/image/1l1d0g0U093r/Screen%20Shot%202013-08-06%20at%204.12.29%20PM.png)

Addresses #127.