Added bunch of javadocs and restricted some visibility.

No functional changes

src/main/java/org/scribe/exceptions/OAuthException.java

@@ -1,18 +1,33 @@
 package org.scribe.exceptions;
 
+/**
+ * Default scribe exception. 
+ * Represents a problem in the OAuth signing process
+ * 
+ * @author Pablo Fernandez
+ */
 public class OAuthException extends RuntimeException
 {
 
+  /**
+   * Default constructor 
+   * @param message message explaining what went wrong
+   * @param e original exception
+   */
   public OAuthException(String message, Exception e)
   {
     super(message, e);
   }
 
+  /**
+   * No-exception constructor. Used when there is no original exception
+   *  
+   * @param message message explaining what went wrong
+   */
   public OAuthException(String message)
   {
     super(message, null);
   }
 
   private static final long serialVersionUID = 1L;
-
 }