Use `Priority: optional` and reorder some fields

`Priority: extra` is deprecated
https://www.debian.org/doc/debian-policy/ch-archive.html#s-priorities

Change-Id: I2cfa0432240452a8fdd5e0b4a2fb8b4c908db612
diff --git a/ndnmap-data-collector/debian/control b/ndnmap-data-collector/debian/control
index 195fb99..0350dc6 100644
--- a/ndnmap-data-collector/debian/control
+++ b/ndnmap-data-collector/debian/control
@@ -1,19 +1,19 @@
 Source: ndnmap-data-collector
-Priority: extra
+Section: net
+Priority: optional
 Maintainer: John DeHart <jdd@wustl.edu>
 Build-Depends: debhelper (>= 9.20160709),
  python3 (>= 3.6.0),
  pkg-config (>= 0.26),
  libndn-cxx-dev (>= 0.8.0)
 Standards-Version: 3.9.2
-Section: net
 Homepage: https://github.com/WU-ARL/ndnmapDataCollector
-Vcs-Git: https://github.com/WU-ARL/ndnmapDataCollector.git
 Vcs-Browser: https://github.com/WU-ARL/ndnmapDataCollector
+Vcs-Git: https://github.com/WU-ARL/ndnmapDataCollector.git
 
 Package: ndnmap-data-collector
 Architecture: i386 amd64 arm64 armel armhf ppc64el
 Depends: ${shlibs:Depends}, ${misc:Depends}, libndn-cxx, ndnsec
-Description: Data collector daemons for ndnmap.arl.wustl.edu
+Description: data collector daemons for ndnmap.arl.wustl.edu
  This tool is designed to generate ndn interests to each NDN Testbed node
  to collect link usage data for display on the ndnmap.arl.wustl.edu web page.