Travisimprovements1

Suggested minor improvements to the travis config; also just testing I understand the github workflow...
Before I get bogged down in detail, my main point is simply that there is no point in issuing a redundant command on Linux, especially one that runs as root. I'll happily remove both comments and add a note to the README.md when you say so. Onto "some docs"...

[RFC 6890] (http://tools.ietf.org/html/rfc6890) defines loopback for IPv4 as "127.0.0.0/8" i.e. 127.0.0.1 through 127.255.255.254 . In practice though, implementation varies.

The earlier version of the RFC, [RFC 5735] (http://tools.ietf.org/html/rfc5735) says "This is ordinarily implemented using only 127.0.0.1/32 for loopback." - which is what OS X appears to do. I haven't managed to find official documentation to show that Linux implements the full RFC definition, but a) experimental evidence shows it seems to be true[0], b) there are a number of discussions on the web mentioning the difference between how Linux and OS X do it.[1]

[0] e.g. ping works for 127.0.0.1 through 127.255.255.254 on a Linux install out of the box
[1] e.g. http://superuser.com/questions/458875/how-do-you-get-loopback-addresses-other-than-127-0-0-1-to-work-on-os-x n.b. it refers to an even earlier version of the RFC, RFC 3330.