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>

pkg/provider/handlers/read.go

@@ -0,0 +1,38 @@
+package handlers
+
+import (
+	"encoding/json"
+	"log"
+	"net/http"
+
+	"github.com/containerd/containerd"
+	"github.com/openfaas/faas-provider/types"
+)
+
+func MakeReadHandler(client *containerd.Client) func(w http.ResponseWriter, r *http.Request) {
+
+	return func(w http.ResponseWriter, r *http.Request) {
+
+		res := []types.FunctionStatus{}
+		funcs, err := ListFunctions(client)
+		if err != nil {
+			log.Printf("[Read] error listing functions. Error: %s\n", err)
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
+		for _, function := range funcs {
+			res = append(res, types.FunctionStatus{
+				Name:      function.name,
+				Image:     function.image,
+				Replicas:  uint64(function.replicas),
+				Namespace: function.namespace,
+			})
+		}
+
+		body, _ := json.Marshal(res)
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusOK)
+		w.Write(body)
+
+	}
+}