Fix Travis not pushing gh-pages for tags
Fix Travis not pushing gh-pages for tags

Turns out $TRAVIS_BRANCH is the tag name for tags.

graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust