Fixed bug: Accessing method on null object

Fixed bug on accessing a method on null object. Changed to a simple comparison.
Signed-off-by: Bruno Nocera Zanette <brunonzanette@gmail.com>

src/main/java/br/ufpr/c3sl/sapos/models/util/PermissionProvider.java

@@ -98,7 +98,7 @@ public class PermissionProvider {
 
 		System.out.println("Executando hasPermissionToView(1) com o parametro: "+id);
 		
-		if (id.equals(null))
+		if (id == null)
 			return false;
 		
 		if (personAuth().equals(Aluno))
@@ -127,7 +127,7 @@ public class PermissionProvider {
 
 		System.out.println("Executando hasPermissionToViewCourse(1) com o parametro: "+id);
 		
-		if (id.equals(null))
+		if (id == null)
 			return false;
 
 		if (personAuth().equals(Aluno))
@@ -154,7 +154,7 @@ public class PermissionProvider {
 
 		System.out.println("Executando hasPermissionToViewSectionpos(1) com o parametro: "+id);
 		
-		if (id.equals(null))
+		if (id == null)
 			return false;
 		
 		if (personAuth().equals(Aluno))