Allow configuration of vim bundle directory
Allow configuration of vim bundle directory

Vim 8 introduced packages. A package is a combination of one or more
plugins in a specific directory layout. Plugins in
".vim/pack/{some_pack_name}/start" get loaded on vim startup.

This commit enables voom to load plugins into a different directory than
into the default ".vim/bundle".

    VIM_BUNDLE_DIR="$HOME/.vim/pack/bundle/start" voom

See-Also: `:help packages`

airblade/voom