Cleaning up Javadocs in core-ui classes.
Added common constants to AbstractCellFormatter.

Change-Id: Ie20ea62f059646e7d6c7f3660dd60a60c40532fe
diff --git a/core/api/src/main/java/org/onosproject/ui/table/cell/NumberFormatter.java b/core/api/src/main/java/org/onosproject/ui/table/cell/NumberFormatter.java
index 597a8a4..93c0754 100644
--- a/core/api/src/main/java/org/onosproject/ui/table/cell/NumberFormatter.java
+++ b/core/api/src/main/java/org/onosproject/ui/table/cell/NumberFormatter.java
@@ -22,7 +22,7 @@
 import java.text.NumberFormat;
 
 /**
- * Formats number using the specified format string".
+ * Formats number using the specified format string.
  */
 public final class NumberFormatter extends AbstractCellFormatter {