Fixed very minor typos in testing code

src/test/java/org/umlgraph/test/BasicTest.java

@@ -98,7 +98,7 @@ public class BasicTest {
     private static List<String> getViewList(File viewFolder) {
 	if (!viewFolder.exists())
 	    throw new RuntimeException("The folder " + viewFolder.getAbsolutePath()
-		    + " does not exists.");
+		    + " does not exist.");
 	else if (!viewFolder.isDirectory())
 	    throw new RuntimeException(viewFolder.getAbsolutePath() + " is not a folder!.");
 	else if (!viewFolder.canRead())

src/test/java/org/umlgraph/test/UmlDocTest.java

@@ -92,10 +92,10 @@ public class UmlDocTest {
 	    return;
 	
 	if (!refFolder.exists() || !refFolder.isDirectory())
-	    throw new IllegalArgumentException("Reference does not exists or is not a folder: "
+	    throw new IllegalArgumentException("Reference does not exist or is not a folder: "
 		    + refFolder.getAbsolutePath());
 	if (!outFolder.exists() || !outFolder.isDirectory())
-	    throw new IllegalArgumentException("Output does not exists or is not a folder: "
+	    throw new IllegalArgumentException("Output does not exist or is not a folder: "
 		    + outFolder.getAbsolutePath());
 
 	// get elements and sort