The words “mortgagor,” “mortgagee,” “judgment creditor,” “judgment debtor” and “purchaser,” whenever used in Sections 89-1-301 through 89-1-329, shall be construed to include the plural as well as the singular and also to include their personal representatives, successors and assigns, and the word “mortgage” shall be construed to include deeds of trust and vendors’ liens; and for purposes of Sections 89-1-301 through 89-1-329, deeds of trust and any instrument executed as security for an indebtedness shall be treated as a mortgage.