updated travis file to install xclip on container
updated travis file to install xclip on container

VSCodeVim/Vim,westim/Vim,Chillee/Vim,Chillee/VSCodeNeovim,westim/Vim,Chillee/VSCodeNeovim,VSCodeVim/Vim,Chillee/VSCodeNeovim,Chillee/Vim,westim/Vim,rufusroflpunch/Vim,rufusroflpunch/Vim