Fix rsvp at v 2.0.4, workaround Travis failure.
Fix rsvp at v 2.0.4, workaround Travis failure.

At v3.0, rsvp no longer contains lib/, so we fall over.
I opened https://github.com/tildeio/rsvp.js/issues/182.
and https://github.com/google/traceur-compiler/issues/618

TBR=johnjbarton

Review URL: https://github.com/google/traceur-compiler/pull/619

Closes #619.

vicb/traceur-compiler,bazaarvoice/traceur-compiler,longze/traceur-compiler,longze/traceur-compiler,renie/traceur-compiler,kittens/traceur-compiler,astralfoxy/mirai-traceur,rossberg-chromium/traceur-soundscript,renie/traceur-compiler,bazaarvoice/traceur-compiler,ericmckean/traceur-compiler,google/traceur-compiler,bjlxj2008/traceur-compiler,guybedford/traceur-compiler,bjlxj2008/traceur-compiler,johnjbarton/traceur-compiler,wilsonokibe/traceur-compiler,sebmck/traceur-compiler,mathiasbynens/traceur-compiler,pandoraui/traceur-compiler,sebgod/traceur-compiler,pandoraui/traceur-compiler,sebmck/traceur-compiler,wilsonokibe/traceur-compiler,sebgod/traceur-compiler,kittens/traceur-compiler,lintangarief/traceur-compiler,sid0818/traceur-compiler,ericmckean/traceur-compiler,sid0818/traceur-compiler,arv/traceur-compiler,google/traceur-compiler,rossberg-chromium/traceur-soundscript,vicb/traceur-compiler,johnjbarton/traceur-compiler,lintangarief/traceur-compiler,arv/traceur-compiler