1. update clientset, deepcopy using code-generator

2. add a dummy file tools.go to force "go mod vendor" to see
code-generator as dependencies
3. add a script to update CRD
4. add a README to document CRD updating steps
run go mod tidy
update README

vendor/github.com/PuerkitoBio/purell/.travis.yml

@@ -0,0 +1,12 @@
+language: go
+
+go:
+    - 1.4.x
+    - 1.5.x
+    - 1.6.x
+    - 1.7.x
+    - 1.8.x
+    - 1.9.x
+    - "1.10.x"
+    - "1.11.x"
+    - tip