(.travis.yml) : Add apt-get update because error occurs in recent travis test reported in https://github.com/euslisp/EusLisp/pull/40
(.travis.yml) : Add apt-get update because error occurs in recent travis test reported in https://github.com/euslisp/EusLisp/pull/40

wkentaro/EusLisp,aginika/EusLisp,wkentaro/EusLisp,aginika/EusLisp,wkentaro/EusLisp,wkentaro/EusLisp,aginika/EusLisp,aginika/EusLisp,bmagyar/EusLisp,bmagyar/EusLisp,bmagyar/EusLisp,bmagyar/EusLisp