Initial merge of faas-containerd

This patch completes part of the work in #20 by porting the code
for faas-containerd in-tree. When tested, I was able to deploy
and then remove figlet from the store on `x86_64`.

In a follow-up PR, duplication will be removed where possible
and consolidated with updated documentation.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

vendor/github.com/openfaas/faas/gateway/requests/forward_request.go

@@ -0,0 +1,29 @@
+package requests
+
+import "fmt"
+import "net/url"
+
+// ForwardRequest for proxying incoming requests
+type ForwardRequest struct {
+	RawPath  string
+	RawQuery string
+	Method   string
+}
+
+// NewForwardRequest create a ForwardRequest
+func NewForwardRequest(method string, url url.URL) ForwardRequest {
+	return ForwardRequest{
+		Method:   method,
+		RawQuery: url.RawQuery,
+		RawPath:  url.Path,
+	}
+}
+
+// ToURL create formatted URL
+func (f *ForwardRequest) ToURL(addr string, watchdogPort int) string {
+	if len(f.RawQuery) > 0 {
+		return fmt.Sprintf("http://%s:%d%s?%s", addr, watchdogPort, f.RawPath, f.RawQuery)
+	}
+	return fmt.Sprintf("http://%s:%d%s", addr, watchdogPort, f.RawPath)
+
+}

vendor/github.com/openfaas/faas/gateway/requests/prometheus.go

@@ -0,0 +1,23 @@
+// Copyright (c) Alex Ellis 2017. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+package requests
+
+// PrometheusInnerAlertLabel PrometheusInnerAlertLabel
+type PrometheusInnerAlertLabel struct {
+	AlertName    string `json:"alertname"`
+	FunctionName string `json:"function_name"`
+}
+
+// PrometheusInnerAlert PrometheusInnerAlert
+type PrometheusInnerAlert struct {
+	Status string                    `json:"status"`
+	Labels PrometheusInnerAlertLabel `json:"labels"`
+}
+
+// PrometheusAlert as produced by AlertManager
+type PrometheusAlert struct {
+	Status   string                 `json:"status"`
+	Receiver string                 `json:"receiver"`
+	Alerts   []PrometheusInnerAlert `json:"alerts"`
+}

vendor/github.com/openfaas/faas/gateway/requests/requests.go

@@ -0,0 +1,18 @@
+// Copyright (c) Alex Ellis 2017. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+// Package requests package provides a client SDK or library for
+// the OpenFaaS gateway REST API
+package requests
+
+// AsyncReport is the report from a function executed on a queue worker.
+type AsyncReport struct {
+	FunctionName string  `json:"name"`
+	StatusCode   int     `json:"statusCode"`
+	TimeTaken    float64 `json:"timeTaken"`
+}
+
+// DeleteFunctionRequest delete a deployed function
+type DeleteFunctionRequest struct {
+	FunctionName string `json:"functionName"`
+}