Add screenshots to ignored dirs in bundlebuilder

After add the directory to the IGNORE_DIRS array,
we need make the standard procedure to get the list off files
for the bundle, get_files_in_git honor the configured ignored
files and dirs. That was not a problem until now,
because that files was already not added to git,
but in the case of the screenshots, are included in git,
but we don't want include them in our bundles.

src/sugar3/activity/bundlebuilder.py

@@ -37,7 +37,7 @@ from sugar3 import env
 from sugar3.bundle.activitybundle import ActivityBundle
 
 
-IGNORE_DIRS = ['dist', '.git']
+IGNORE_DIRS = ['dist', '.git', 'screenshots']
 IGNORE_FILES = ['.gitignore', 'MANIFEST', '*.pyc', '*~', '*.bak', 'pseudo.po']
 
 
@@ -188,7 +188,22 @@ class Packager(object):
                               IGNORE_DIRS, IGNORE_FILES)
         if stdout:
             # pylint: disable=E1103
-            return [path.strip() for path in stdout.strip('\n').split('\n')]
+            git_output = [path.strip() for path in
+                          stdout.strip('\n').split('\n')]
+            files = []
+            for line in git_output:
+                ignore = False
+                for directory in IGNORE_DIRS:
+                    if line.startswith(directory + '/'):
+                        ignore = True
+                        break
+                if not ignore:
+                    files.append(line)
+
+            for pattern in IGNORE_FILES:
+                files = [f for f in files if not fnmatch(f, pattern)]
+
+            return files
         else:
             return list_files(self.config.source_dir,
                               IGNORE_DIRS, IGNORE_FILES)