Cleaning up Javadocs in core-ui classes.
Promoted Glyphs inner class to GlyphConstants.

Change-Id: Ib12a4556a75d98edb3544b9ae45605fab554fdcf
diff --git a/core/api/src/main/java/org/onosproject/ui/UiMessageHandler.java b/core/api/src/main/java/org/onosproject/ui/UiMessageHandler.java
index a2d847f..f6c1535 100644
--- a/core/api/src/main/java/org/onosproject/ui/UiMessageHandler.java
+++ b/core/api/src/main/java/org/onosproject/ui/UiMessageHandler.java
@@ -154,16 +154,16 @@
     }
 
     /**
-     * Returns the user interface connection with which this handler was primed.
+     * Returns the service directory with which this handler was primed.
      *
-     * @return user interface connection
+     * @return service directory
      */
     public ServiceDirectory directory() {
         return directory;
     }
 
     /**
-     * Returns implementation of the specified service class.
+     * Returns an implementation of the specified service class.
      *
      * @param serviceClass service class
      * @param <T>          type of service