fix(travis): disable node 4 for now
fix(travis): disable node 4 for now

throws errors everywhere regarding the compiler, nan, and node 4.1.2

nirmit/nylas-mail,nylas-mail-lives/nylas-mail,nylas-mail-lives/nylas-mail,nirmit/nylas-mail,nylas-mail-lives/nylas-mail,nylas/nylas-mail,nylas-mail-lives/nylas-mail,nirmit/nylas-mail,simonft/nylas-mail,nirmit/nylas-mail,nylas/nylas-mail,simonft/nylas-mail,simonft/nylas-mail,simonft/nylas-mail,nirmit/nylas-mail,simonft/nylas-mail,nylas/nylas-mail,nylas-mail-lives/nylas-mail,nylas/nylas-mail,nylas/nylas-mail