use istio client-go library instead of knative (#1661)

use istio client-go library instead of knative
bump kubernetes dependency version
change code coverage to codecov

vendor/github.com/mattn/go-isatty/.travis.yml

@@ -0,0 +1,13 @@
+language: go
+go:
+  - tip
+
+os:
+  - linux
+  - osx
+
+before_install:
+  - go get github.com/mattn/goveralls
+  - go get golang.org/x/tools/cmd/cover
+script:
+  - $HOME/gopath/bin/goveralls -repotoken 3gHdORO5k5ziZcWMBxnd9LrMZaJs8m9x5