Fix failure on Travis because of telling tar to extract a gzip archive while it's already unpacked.
Fix failure on Travis because of telling tar to extract a gzip archive while it's already unpacked.

Apperantly OS X's BSD tar accepts the x option even if the archive is not a gzip archive.

dnkoutso/Core,Ashton-W/Core,brianmichel/Core,orta/Core,dacaiguoguogmail/Core,gabro/Core,AdamCampbell/Core,k0nserv/Core,CocoaPods/Core