add travis

.travis.yml

@@ -0,0 +1,20 @@
+language: go
+go:
+    - 1.7
+    - 1.8
+    - tip
+before_install:
+    - export PATH=$PATH:$GOPATH/bin
+    - go get github.com/modocache/gover
+    - go get github.com/mattn/goveralls
+    - go get golang.org/x/tools/cmd/cover
+install:
+    - go get -t -v ./...
+script:
+    - diff -u <(echo -n) <(gofmt -d -s $(find . -type f -name '*.go'))
+    - go test -test.v -race -coverprofile=ratelimit.coverprofile
+    - gover
+    - goveralls -coverprofile=gover.coverprofile -service=travis-ci
+matrix:
+  allow_failures:
+    - go: tip