Reorganize packages, closes #79

- All packages go into either cmd or pkg directories
- Most packages renamed
- Server packages moved into pkg/server
- sanitize moved into webui, as that's the only place it's used
- filestore moved into pkg/storage/file
- Makefile updated, and PKG variable use fixed

pkg/rest/client/rest.go

@@ -0,0 +1,59 @@
+package client
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+)
+
+// httpClient allows http.Client to be mocked for tests
+type httpClient interface {
+	Do(*http.Request) (*http.Response, error)
+}
+
+// Generic REST restClient
+type restClient struct {
+	client  httpClient
+	baseURL *url.URL
+}
+
+// do performs an HTTP request with this client and returns the response
+func (c *restClient) do(method, uri string) (*http.Response, error) {
+	rel, err := url.Parse(uri)
+	if err != nil {
+		return nil, err
+	}
+
+	url := c.baseURL.ResolveReference(rel)
+
+	// Build the request
+	req, err := http.NewRequest(method, url.String(), nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Send the request
+	return c.client.Do(req)
+}
+
+// doGet performs an HTTP request with this client and marshalls the JSON response into v
+func (c *restClient) doJSON(method string, uri string, v interface{}) error {
+	resp, err := c.do(method, uri)
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		_ = resp.Body.Close()
+	}()
+	if resp.StatusCode == http.StatusOK {
+		if v == nil {
+			return nil
+		}
+		// Decode response body
+		return json.NewDecoder(resp.Body).Decode(v)
+	}
+
+	return fmt.Errorf("Unexpected HTTP response status %v: %s", resp.StatusCode, resp.Status)
+}