Add Aptly REST API methods

This pathch adds methods to work with Aptly by Aptly REST API.

Change-Id: I69c7531ab1605a78971f97eba283c54eea98712f
diff --git a/src/com/mirantis/mk/Http.groovy b/src/com/mirantis/mk/Http.groovy
index 7e22ca6..e14a523 100644
--- a/src/com/mirantis/mk/Http.groovy
+++ b/src/com/mirantis/mk/Http.groovy
@@ -184,6 +184,16 @@
 }
 
 /**
+ * Make DELETE request using Salt REST API and return parsed JSON
+ *
+ * @param master   Salt connection object
+ * @param uri   URI which will be appended to Salt server base URL
+ */
+def restDelete(master, uri, data = null) {
+    return restCall(master, uri, 'DELETE', data)
+}
+
+/**
  * Set HTTP and HTTPS proxy for running JVM
  * @param host HTTP proxy host
  * @param port HTTP proxy port