Add support for downloading a document's OCR text.

Closes GitLab issue #215.

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

mayan/apps/ocr/links.py

@@ -41,3 +41,8 @@ link_document_ocr_erros_list = Link(
     permissions=(permission_ocr_content_view,), text=_('OCR errors'),
     view='ocr:document_ocr_error_list'
 )
+link_document_ocr_download = Link(
+    args='resolved_object.id', icon='fa fa-file-text-o',
+    permissions=(permission_ocr_content_view,), text=_('Download OCR text'),
+    view='ocr:document_ocr_download'
+)