Removed redundant \d from regex character class that already has \w.
Removed redundant \d from regex character class that already has \w.

This was causing the following warning during Rails test suite:

gems/ruby-1.9.2-p180/gems/mail-2.3.0/lib/mail/fields/common/parameter_hash.rb:32: warning: character class has duplicated range: /([\w\d\-]+)'(\w\w)'(.*)/
pjskennedy/mail,pushrax/mail,kjg/mail,zacholauson/mail,smallspark/mail,planio-gmbh/mail,carsonreinke/mail,kaineer/mail,jeremyevans/mail,schneems/mail,yujinakayama/mail,jeremy/mail,agaridata/mail,EdwardPantoja/mail,pjskennedy/mail,agaridata/mail,Schniz/mail,benmmurphy/mail,pushrax/mail,carsonreinke/mail,wktk/mail,smallspark/mail,pascalbetz/mail,wktk/mail,jeremyevans/mail,jonkgrimes/mail,kaineer/mail,kainlite/mail,schneems/mail,schepedw/mail,kjg/mail,0x00evil/mail,0x00evil/mail,zacholauson/mail,kert-io/mail,benmmurphy/mail,missive/mail,schepedw/mail,EdwardPantoja/mail,jonkgrimes/mail,owenr/mail,jeremy/mail,mikel/mail,kert-io/mail