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

.travis.yml

@@ -10,6 +10,7 @@ git:
 
 go:
   - "1.12.x"
+  - "tip"
 env:
   - GO111MODULE=on
 cache:
@@ -23,11 +24,13 @@ before_script:
 script:
   - diff -u <(echo -n) <(gofmt -d ./pkg ./cmd ./tools)
   - make openapi
-  - make all && $HOME/gopath/bin/goveralls -coverprofile=cover.out -service=travis-ci -repotoken=$COVERALLS_TOKEN
+  - make all 
 
-install:
-  - go get golang.org/x/tools/cmd/cover
-  - go get github.com/mattn/goveralls
+before_install:
+  - go get -t -v ./...
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)
 
 deploy:
   skip_cleanup: true