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/hashicorp/raft/stable.go

@@ -0,0 +1,15 @@
+package raft
+
+// StableStore is used to provide stable storage
+// of key configurations to ensure safety.
+type StableStore interface {
+	Set(key []byte, val []byte) error
+
+	// Get returns the value for key, or an empty byte slice if key was not found.
+	Get(key []byte) ([]byte, error)
+
+	SetUint64(key []byte, val uint64) error
+
+	// GetUint64 returns the uint64 value for key, or 0 if key was not found.
+	GetUint64(key []byte) (uint64, error)
+}