Update .travis.yml

.travis.yml

 language: go
 go:
-- 1.10
+- "1.10"
 - master
 before_install:
 - mkdir -p $GOPATH/src/github.com/bio-routing
 - ln -s $TRAVIS_BUILD_DIR $HOME/gopath/src/github.com/bio-routing/ || true
 - go get github.com/mattn/goveralls
 script:
-- goveralls -v
\ No newline at end of file
+- goveralls -v