Update .travis.yml

Hopefully fixing Travis' out of date ass.

Their docs DO NOT AGREE with themselves as far as what versions are available. Go 1.0 is clearly default, and stupid as shit.

Observe:

"Travis CI support Go 1.0, which is installed by default, but you can also use 1.1 and the latest Go version from tip."

and: 

"Travis CI currently only provides a single Go version, 1.0."