truncate long ip addresses (ipv6)

ipv6 addresses (and maybe onion addresses) are too long to fit into the peers window.

this patch truncates long addresses with `...`

![screenshot-7](https://cloud.githubusercontent.com/assets/6561620/5533549/c3b7aff6-8a4a-11e4-8212-85529fd2e6d4.png)