Added a detailed example of handling attachments to the README
Added a detailed example of handling attachments to the README

The README didn't include details on how one was expected to
extract binary data from an attachment. Now it does.

missive/mail,kaineer/mail,jonkgrimes/mail,jeremy/mail,jeremy/mail,zacholauson/mail,pascalbetz/mail,schepedw/mail,pjskennedy/mail,jeremyevans/mail,EdwardPantoja/mail,owenr/mail,zacholauson/mail,schneems/mail,planio-gmbh/mail,kjg/mail,jonkgrimes/mail,EdwardPantoja/mail,benmmurphy/mail,pjskennedy/mail,pushrax/mail,kainlite/mail,pushrax/mail,smallspark/mail,schneems/mail,benmmurphy/mail,Schniz/mail,yujinakayama/mail,schepedw/mail,carsonreinke/mail,0x00evil/mail,agaridata/mail,jeremyevans/mail,0x00evil/mail,wktk/mail,agaridata/mail,kert-io/mail,smallspark/mail,mikel/mail,kjg/mail,kert-io/mail,wktk/mail,carsonreinke/mail,kaineer/mail