bash.bashrc: source vte.sh if existing (bnc#827248)

Source /etc/profile.d/vte.sh, which improvies usage of VTE based terminals.
It is vte.sh's responsibility to 'not load' when it's not applicable (not inside a VTE term)
If you want to 'disable' this functionality, set the sticky bit on /etc/profile.d/vte.sh