Use Ubuntu 14.04 Trusty Tahr for Travis CI
Use Ubuntu 14.04 Trusty Tahr for Travis CI

Trusty Tahr includes vim 7.4 while Travis CI's default Precise Pangolin
only includes vim 7.3. However, the functionality-test "no change in
<,>-marks" fails with vim 7.3 and it does not with vim 7.4.
Hence, we use Trusty Tahr. Here, bundler has to be installed manually as
well.

For an experience that is as bug-free as possible, use vim with a
version >= 7.4.

milsen/vim-operator-substitute