initial xlint implementation. Accumulate all import errors during XmlModuleStore importing. Also do checks post XmlModuleStore import and assert that the structure (course->chapter->sequential->vertical) is present in the courses.

cms/djangoapps/contentstore/management/commands/xlint.py

@@ -9,8 +9,10 @@ unnamed_modules = 0
 
 class Command(BaseCommand):
     help = \
-'''Verify the structure of courseware as to it's suitability for import'''
-
+    '''
+    Verify the structure of courseware as to it's suitability for import
+    To run test: rake cms:xlint DATA_DIR=../data [COURSE_DIR=content-edx-101 (optional parameter)]
+    '''
     def handle(self, *args, **options):
         if len(args) == 0:
             raise CommandError("import requires at least one argument: <data directory> [<course dir>...]")