Add support for PDF attachments. Fixes bug #325143

Add support for PDF attachments. Fixes bug #325143

	* backend/Makefile.am:
	* data/evince-ui.xml:
	* backend/ev-attachment.[ch]:
	* backend/ev-document.[ch]: (ev_document_has_attachments),
	(ev_document_get_attachments):
	* pdf/ev-poppler.cc: (pdf_document_has_attachments),
	(attachment_save_to_buffer), (pdf_document_get_attachments),
	(pdf_document_document_iface_init):
	* shell/Makefile.am:
	* shell/ev-attachment-bar.[ch]:
	* shell/ev-window.c:

 	Add support for PDF attachments. Fixes bug #325143