Add more theme color options

Porting work from OpenStack Gerrit.
* Adds a theme option to change outdated background color, the default
is too harsh for some themes.
* Adds odd/even row background color for tables such as list of open
reviews.  This makes them more visible without clicking on them.

Change-Id: I86ad9bba0f6cfffb267dd2631cc718c5c10e848a

gerrit-common/src/main/java/com/google/gerrit/common/data/HostPageData.java

@@ -31,5 +31,8 @@ public class HostPageData {
     public String textColor;
     public String trimColor;
     public String selectionColor;
+    public String changeTableOutdatedColor;
+    public String tableOddRowColor;
+    public String tableEvenRowColor;
   }
 }