Update HEADER_PATTERN for Ruby 1.9 compatibility
Update HEADER_PATTERN for Ruby 1.9 compatibility

tenderlove/sprockets,spodlecki/sprockets,recursecenter/sprockets,eileencodes/sprockets,byroot/sprockets,basecamp/sprockets,bdezonia/sprockets,Andreis13/sprockets,daniel-rikowski/sprockets,sferik/sprockets,elia/sprockets,tricknotes/sprockets,dollarshaveclub/sprockets,prathamesh-sonpatki/sprockets,guilleiguaran/sprockets,jcoyne/sprockets,prusswan/sprockets,JuanitoFatas/sprockets,schneems/sprockets,askl56/sprockets,jeremy/sprockets,IvanAnaniev/sprockets,orlando/sprockets,kappezoro/sprockets,masarakki/sprockets,finnlabs/sprockets,maclover7/sprockets,rails/sprockets,sideci-sample/sideci-sample-sprockets