Add pdf to documents tuple (#20)

Author: greyli

flask_uploads.py

@@ -35,7 +35,7 @@
 #: This contains various office document formats (.rtf, .odf, .ods, .gnumeric,
 #: .abw, .doc, .docx, .xls, and .xlsx). Note that the macro-enabled versions
 #: of Microsoft Office 2007 files are not included.
-DOCUMENTS = tuple('rtf odf ods gnumeric abw doc docx xls xlsx'.split())
+DOCUMENTS = tuple('rtf odf ods gnumeric abw doc docx xls xlsx pdf'.split())
 
 #: This contains basic image types that are viewable from most browsers (.jpg,
 #: .jpe, .jpeg, .png, .gif, .svg, and .bmp).