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/log.go

@@ -0,0 +1,72 @@
+package raft
+
+// LogType describes various types of log entries.
+type LogType uint8
+
+const (
+	// LogCommand is applied to a user FSM.
+	LogCommand LogType = iota
+
+	// LogNoop is used to assert leadership.
+	LogNoop
+
+	// LogAddPeer is used to add a new peer. This should only be used with
+	// older protocol versions designed to be compatible with unversioned
+	// Raft servers. See comments in config.go for details.
+	LogAddPeerDeprecated
+
+	// LogRemovePeer is used to remove an existing peer. This should only be
+	// used with older protocol versions designed to be compatible with
+	// unversioned Raft servers. See comments in config.go for details.
+	LogRemovePeerDeprecated
+
+	// LogBarrier is used to ensure all preceding operations have been
+	// applied to the FSM. It is similar to LogNoop, but instead of returning
+	// once committed, it only returns once the FSM manager acks it. Otherwise
+	// it is possible there are operations committed but not yet applied to
+	// the FSM.
+	LogBarrier
+
+	// LogConfiguration establishes a membership change configuration. It is
+	// created when a server is added, removed, promoted, etc. Only used
+	// when protocol version 1 or greater is in use.
+	LogConfiguration
+)
+
+// Log entries are replicated to all members of the Raft cluster
+// and form the heart of the replicated state machine.
+type Log struct {
+	// Index holds the index of the log entry.
+	Index uint64
+
+	// Term holds the election term of the log entry.
+	Term uint64
+
+	// Type holds the type of the log entry.
+	Type LogType
+
+	// Data holds the log entry's type-specific data.
+	Data []byte
+}
+
+// LogStore is used to provide an interface for storing
+// and retrieving logs in a durable fashion.
+type LogStore interface {
+	// FirstIndex returns the first index written. 0 for no entries.
+	FirstIndex() (uint64, error)
+
+	// LastIndex returns the last index written. 0 for no entries.
+	LastIndex() (uint64, error)
+
+	// GetLog gets a log entry at a given index.
+	GetLog(index uint64, log *Log) error
+
+	// StoreLog stores a log entry.
+	StoreLog(log *Log) error
+
+	// StoreLogs stores multiple log entries.
+	StoreLogs(logs []*Log) error
+
+	// DeleteRange deletes a range of log entries. The range is inclusive.
+	DeleteRange(min, max uint64) error
+}