Travis CI: Remove now-unused $GEMDIR env var
Travis CI: Remove now-unused $GEMDIR env var

[skip sauce]
joblocal/bootstrap,stanwmusic/bootstrap,n054/bootstrap,fschumann1211/bootstrap,seanwu99/bootstrap,seanwu99/bootstrap,abvalentine/bootstrap,inway/bootstrap,gijsbotje/bootstrap,copperdesign/bootstrap,tomlutzenberger/bootstrap,peterblazejewicz/bootstrap,xt0rted/bootstrap,Scoutski/bootstrap,tagliala/bootstrap,JumpLinkNetwork/bootstrap-backward,n054/bootstrap,slavanga/bootstrap,nice-fungal/bootstrap,johnajacob/bootstrap,vsn4ik/bootstrap,wesamco/bootstrap-rtl,frostbitten/bootstrap,hebbet/bootstrap,GerHobbelt/bootstrap,Scoutski/bootstrap,tibo66/bootstrap,bootstrapbrasil/bootstrap,bardiharborow/bootstrap,9-chirno/chirno,xt0rted/bootstrap,TheFridayInstitute/bootstrap,tibo66/bootstrap,tjkohli/bootstrap,lemuelbarango/bootstrap,n054/bootstrap,abvalentine/bootstrap,edanbarak/bootstrap,abvalentine/bootstrap,inway/bootstrap,IdanCo/bootstrap,tjkohli/bootstrap,sealocal/bootstrap,lipis/bootstrap,peterblazejewicz/bootstrap,andresgalante/bootstrap,m5o/bootstrap,andresgalante/bootstrap,creativewebjp/bootstrap,hebbet/bootstrap,m5o/bootstrap,slavanga/bootstrap,supergibbs/bootstrap,jipexu/bootstrap,Hemphill/bootstrap-docs,yuyokk/bootstrap,gijsbotje/bootstrap,fschumann1211/bootstrap,edanbarak/bootstrap,jipexu/bootstrap,zalog/bootstrap,Lyricalz/bootstrap,frostbitten/bootstrap,kvlsrg/bootstrap,xt0rted/bootstrap,slavanga/bootstrap,lemuelbarango/bootstrap,seanwu99/bootstrap,NCARB/bootstrap,hebbet/bootstrap,bardiharborow/bootstrap,copperdesign/bootstrap,9-chirno/chirno,nice-fungal/bootstrap,lipis/bootstrap,wesamco/bootstrap-rtl,supergibbs/bootstrap,gijsbotje/bootstrap,yuyokk/bootstrap,Scoutski/bootstrap,tomlutzenberger/bootstrap,jipexu/bootstrap,fschumann1211/bootstrap,sealocal/bootstrap,9-chirno/chirno,wesamco/bootstrap-rtl,coliff/bootstrap,stanwmusic/bootstrap,janseliger/bootstrap,gijsbotje/bootstrap,abvalentine/bootstrap,Delagen/bootstrap,realcrowd/bootstrap,igoynawamreh/bootstrap,tagliala/bootstrap,SweetProcess/bootstrap,nice-fungal/bootstrap,janseliger/bootstrap,lipis/bootstrap,Hemphill/bootstrap-docs,Hemphill/bootstrap-docs,copperdesign/bootstrap,lipis/bootstrap,afuno/bootstrap,johnajacob/bootstrap,sealocal/bootstrap,SweetProcess/bootstrap,coliff/bootstrap,IdanCo/bootstrap,janseliger/bootstrap,Delagen/bootstrap,igoynawamreh/bootstrap,fschumann1211/bootstrap,twbs/bootstrap,Delagen/bootstrap,yuyokk/bootstrap,TheFridayInstitute/bootstrap,Lyricalz/bootstrap,vsn4ik/bootstrap,joblocal/bootstrap,JumpLinkNetwork/bootstrap-backward,afuno/bootstrap,johnajacob/bootstrap,GerHobbelt/bootstrap,igoynawamreh/bootstrap,jipexu/bootstrap,IdanCo/bootstrap,zalog/bootstrap,GerHobbelt/bootstrap,frostbitten/bootstrap,tibo66/bootstrap,stanwmusic/bootstrap,Hemphill/bootstrap-docs,JumpLinkNetwork/bootstrap-backward,davethegr8/bootstrap,frostbitten/bootstrap,NCARB/bootstrap,tagliala/bootstrap,joblocal/bootstrap,supergibbs/bootstrap,inway/bootstrap,creativewebjp/bootstrap,Lyricalz/bootstrap,Lyricalz/bootstrap,davethegr8/bootstrap,Scoutski/bootstrap,tibo66/bootstrap,bootstrapbrasil/bootstrap,joblocal/bootstrap,copperdesign/bootstrap,kvlsrg/bootstrap,sealocal/bootstrap,9-chirno/chirno,slavanga/bootstrap,realcrowd/bootstrap,Hightrack/bootstrap,janseliger/bootstrap,xt0rted/bootstrap,stanwmusic/bootstrap,bardiharborow/bootstrap,JumpLinkNetwork/bootstrap-backward,johnajacob/bootstrap,SweetProcess/bootstrap,Hightrack/bootstrap,afuno/bootstrap,afuno/bootstrap,zalog/bootstrap,tomlutzenberger/bootstrap,TheFridayInstitute/bootstrap,edanbarak/bootstrap,seanwu99/bootstrap,igoynawamreh/bootstrap,Delagen/bootstrap,realcrowd/bootstrap,Hightrack/bootstrap,wesamco/bootstrap-rtl,andresgalante/bootstrap,peterblazejewicz/bootstrap,davethegr8/bootstrap,edanbarak/bootstrap,vsn4ik/bootstrap,TheFridayInstitute/bootstrap,twbs/bootstrap,lemuelbarango/bootstrap,yuyokk/bootstrap,IdanCo/bootstrap,bardiharborow/bootstrap,n054/bootstrap,kvlsrg/bootstrap,NCARB/bootstrap,lemuelbarango/bootstrap,realcrowd/bootstrap,vsn4ik/bootstrap,davethegr8/bootstrap,andresgalante/bootstrap,supergibbs/bootstrap,SweetProcess/bootstrap,bootstrapbrasil/bootstrap,creativewebjp/bootstrap,creativewebjp/bootstrap,NCARB/bootstrap,hebbet/bootstrap