import guard for report_xls

The dependency is indeed declared in __openerp__.py and will be
enforced. Odoo evaluates all python files, even for modules which are
not installed, and crashes if an unneeded dependency is needed.

Conflicts:
	mis_builder/report/__init__.py

cherry picked

mis_builder/report/__init__.py

@@ -22,4 +22,13 @@
 #
 ##############################################################################
 
+<<<<<<< HEAD
 from . import mis_builder_xls
+=======
+try:
+    from . import mis_builder_xls
+except ImportError:
+    pass  # this module is not installed
+
+from . import report_mis_report_instance
+>>>>>>> 586ddbe... import guard for report_xls