Afegida taula de classes a utils/db_structure.sql

La taula s'omple per l'script Python table-parser del repositori
principal.

Change-Id: Ied792d52e7c7f41bf2a239b548b1ca3a98822a97
diff --git a/utils/db_structure.sql b/utils/db_structure.sql
index cedf7a6..52aeac6 100644
--- a/utils/db_structure.sql
+++ b/utils/db_structure.sql
@@ -21,4 +21,13 @@
   subject_id INT NOT NULL
 );
 
+CREATE TABLE classes (
+  id INT NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY(id),
+  calendar_name VARCHAR(100) NOT NULL,
+  room VARCHAR(10) NOT NULL,
+  begins DATETIME NOT NULL,
+  ends DATETIME NOT NULL
+);
+
 -- @TODO: Add form completion log table