remove duplicate rake from gemspec
remove duplicate rake from gemspec

loggator/slanger,markburns/slanger,markburns/slanger,stevegraham/slanger,amvse/slanger,daande/slanger,loggator/slanger,carlos-ramos-mojix-com/slanger,notnoopci/slanger,ambrish123456/testSlanger,amvse/slanger,daande/slanger,shaicoleman/slanger,notnoopci/slanger,ambrish123456/testSlanger,shaicoleman/slanger,carlos-ramos-mojix-com/slanger,stevegraham/slanger