Allow configuration of a default value for a label.

This change allows a project admin or owner to define a default value
(or score) for a label. The default value is set in the project configurations
file with a 'defaultValue' key.  The defaultValue must be within the range of
valid label values.  It is an optional label setting, if not defined the
defaultValue for the label will be 0.  When a defaultValue is defined, that
value will get set in the Reply dialog by default.  A defaultValue can be set
to a score that is outside of the permissible range for a user.  In that case
the score that will get set in the Reply box will be the next closes score
to the defaultValue.

feature: Issue 2041
Change-Id: I12dece29b043e09eaab62cdcf56146a1380041bc

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

@@ -112,6 +112,7 @@ public class LabelType {
   protected boolean copyMaxScore;
   protected boolean copyAllScoresOnTrivialRebase;
   protected boolean copyAllScoresIfNoCodeChange;
+  protected short defaultValue;
 
   protected List<LabelValue> values;
   protected short maxNegative;
@@ -129,6 +130,7 @@ public class LabelType {
     this.name = checkName(name);
     canOverride = true;
     values = sortValues(valueList);
+    defaultValue = 0;
 
     abbreviation = defaultAbbreviation(name);
     functionName = "MaxWithBlock";
@@ -204,6 +206,14 @@ public class LabelType {
     return v.getValue() > 0 ? v : null;
   }
 
+  public short getDefaultValue() {
+    return defaultValue;
+  }
+
+  public void setDefaultValue(short defaultValue) {
+    this.defaultValue = defaultValue;
+  }
+
   public boolean isCopyMinScore() {
     return copyMinScore;
   }