fix travis badge
fix travis badge

Summary: oops

Reviewed By: udippant

Differential Revision: D17740544

fbshipit-source-id: da370b2ae39e990545d82fd0da715bfaa2f363bd

facebookincubator/mvfst,facebookincubator/mvfst,facebookincubator/mvfst,facebookincubator/mvfst,facebookincubator/mvfst