Add tags to requirements.yaml for easier deployment of central and edge

Also, bump nem-monitoring chart and fix prometheus scrape endpoints for
nem-kpi-exporter and node-exporter.

Change-Id: I1615c970ac4da55dbd858345a97e1f0738a0d86e
diff --git a/.gitignore b/.gitignore
index 68d93c6..d6b6376 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 requirements.lock
+charts