File metadata: Add file metadata app

Add the file metadata app. This app uses binary wrappers called drivers
to extract properties from the file of documents. The default driver
uses the exiftool to extract the EXIF record from JPEG images.
The exiftool can also extra some properties from other files like
PDFs, office files and sound file.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

mayan/apps/file_metadata/settings.py

@@ -0,0 +1,23 @@
+from __future__ import unicode_literals
+
+from django.utils.translation import ugettext_lazy as _
+
+from mayan.apps.smart_settings import Namespace
+
+from .literals import DEFAULT_EXIF_PATH
+
+namespace = Namespace(name='file_metadata', label=_('File metadata'))
+
+setting_drivers_arguments = namespace.add_setting(
+    global_name='FILE_METADATA_DRIVERS_ARGUMENTS',
+    default={'exif_driver': {'exiftool_path': DEFAULT_EXIF_PATH}}, help_text=_(
+        'Arguments to pass to the drivers.'
+    )
+)
+setting_auto_process = namespace.add_setting(
+    global_name='FILE_METADATA_AUTO_PROCESS', default=True,
+    help_text=_(
+        'Set new document types to perform file metadata processing '
+        'automatically by default.'
+    )
+)