Remove vendor directory and add it to the ignore list

vendor/github.com/sirupsen/logrus/.travis.yml

@@ -1,15 +0,0 @@
-language: go
-go:
-  - 1.6.x
-  - 1.7.x
-  - 1.8.x
-  - tip
-env:
-  - GOMAXPROCS=4 GORACE=halt_on_error=1
-install:
-  - go get github.com/stretchr/testify/assert
-  - go get gopkg.in/gemnasium/logrus-airbrake-hook.v2
-  - go get golang.org/x/sys/unix
-  - go get golang.org/x/sys/windows
-script:
-  - go test -race -v ./...