Added URLDecoding to verifier

src/main/java/org/scribe/model/Verifier.java

@@ -1,5 +1,7 @@
 package org.scribe.model;
 
+import org.scribe.utils.*;
+
 /**
  * Represents an OAuth verifier code.
  * 
@@ -7,6 +9,7 @@ package org.scribe.model;
  */
 public class Verifier
 {
+
   private final String value;
 
   /**
@@ -16,7 +19,7 @@ public class Verifier
    */
   public Verifier(String value)
   {
-    this.value = value;
+    this.value = URLUtils.percentDecode(value);
   }
 
   public String getValue()

src/test/java/org/scribe/model/VerifierTest.java

@@ -0,0 +1,21 @@
+package org.scribe.model;
+
+import static org.junit.Assert.*;
+
+import org.junit.*;
+
+public class VerifierTest
+{
+  @Test
+  public void shouldParse()
+  {
+    Verifier verifier = new Verifier("p8k%2BGIjIL9PblXq%2BpH6LmT9l");
+    assertEquals(verifier.getValue(), "p8k+GIjIL9PblXq+pH6LmT9l");
+  }
+
+  @Test(expected = IllegalArgumentException.class)
+  public void shouldThrowErrorForNullString()
+  {
+    new Verifier(null);
+  }
+}