Add feature to run last spec or last cucumber scenario

[jmgarnier]

See vim-rspec feature:

https://github.com/thoughtbot/vim-rspec/blob/master/plugin/rspec.vim#L39

I am new to vim script so I presume you would go faster than me. If you have no time or don't see the value of this feature, I'll try other plugins and updates the isssue if I find something. If I don't find any alternative, I'll try to add it to vroom.

[jmgarnier]

I found a quick and easy way to run last test with vimux:

map <Leader>l :wa<CR> :VimuxRunLastCommand<CR>

[teohm]

+1 I need this feature too

[jvanbaarsen]

+1

[p0deje]

Sent pull request with this feature in #53