bump to current version of grunt-mailgun (resolves windows issue)
bump to current version of grunt-mailgun (resolves windows issue)

andrebellafronte/grunt-email-workflow,iamchathu/grunt-email-workflow,LucasKA/mail-builder,sherzberg/grunt-email-workflow,brightbytes/email-templater,johndavidsparrow/grunt-email-workflow,vukanac/grunt-email-workflow,Traff1kMike/grunt-email,clecompte/grunt-email-design,brightbytes/email-templater,serjiosilent/grunt-email-design,timripley/grunt-email-workflow,juliusakula/grunt-email-workflow,leemunroe/grunt-email-workflow,andrebellafronte/grunt-email-workflow,LucasKA/mail-builder,rightscale-design/grunt-email-workflow,juliusakula/grunt-email-workflow,cyponthemic/performance-email-future-proof-template,Mizpah/NSTransEmails,porkepic/ccube-email-templates,Xerasset/grunt-email-code,jasonmelgoza/grunt-email-design,19peaches/grunt-email-workflow,timripley/grunt-email-workflow,newswim/geekemail,Mizpah/NSTransEmails,iamchathu/grunt-email-workflow,Traff1kMike/grunt-email,Ye-Ting/email-flow,newswim/geekemail,Xerasset/grunt-email-code,kuzin/EmailGen,taeo/grunt-email-design,johndavidsparrow/grunt-email-workflow,aisensiy/benz_email1,porkepic/ccube-email-templates,taeo/grunt-email-design,19peaches/grunt-email-workflow,Ye-Ting/email-flow,rightscale-design/grunt-email-workflow,serjiosilent/grunt-email-design,kuzin/EmailGen,vukanac/grunt-email-workflow,leemunroe/grunt-email-workflow,jasonmelgoza/grunt-email-design,Webstars/the-weekly