GUI -- Tabular views have divs that encapsulate the header to make math easier for calculating table height. - fixed bug in Device Details Panel where Ports table wouldn't scroll. - Minor refactoring

Change-Id: I2d8133fb4a92f82087566084143c32deb7393fb3
diff --git a/web/gui/src/main/webapp/app/common.css b/web/gui/src/main/webapp/app/common.css
index b188930..d0d878e 100644
--- a/web/gui/src/main/webapp/app/common.css
+++ b/web/gui/src/main/webapp/app/common.css
@@ -18,3 +18,9 @@
  ONOS GUI -- common -- CSS file
  */
 
+#view h2 {
+    margin: 0;
+    /* separated out so that other padding doesn't get clobbered */
+    padding-top: 20px;
+    padding-bottom: 20px;
+}