OCR: Add 'ocr_content' attribute

Add the 'ocr_content' attribute to documents to allow access
to a document's OCR content for indexing and other purposes.

Fixes the OCR indexing failing test.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/ocr/utils.py

@@ -13,6 +13,11 @@ def get_document_ocr_content(document):
         try:
             page_content = page.ocr_content.content
         except DocumentPageOCRContent.DoesNotExist:
-            pass
+            yield ''
         else:
             yield force_text(page_content)
+
+
+@property
+def document_property_ocr_content(self):
+    return ' '.join(get_document_ocr_content(self))