Add HashiCorp Nomad provider (#483)

* provider: adding Nomad provider

* updating CONTRIBUTING.md with Nomad provider

* updated README.md by adding the Nomad provider

* fix typo

* adding nomad/api and nomad/testutil deps

* adding Nomad binary dependency for provider tests

* fixed the nomad binary download command step and added tolerations to the nomad provider.

* adding nomad provider demo gif

* adding my name to authors

* adding two missing go-rootcerts files after dep ensure

* delete pod comment

vendor/github.com/pierrec/lz4/debug_stub.go

@@ -0,0 +1,7 @@
+// +build !lz4debug
+
+package lz4
+
+const debugFlag = false
+
+func debug(args ...interface{}) {}