Merge with NicoSantangelo/SublimeLinter-contrib-flow

Hello! sorry for the delay!

I finally got around [merging](https://github.com/NicoSantangelo/SublimeLinter-contrib-flow/issues/2) the packages. I've splitted the commits in the different features so you can review them separately (and if you don't like any of them, rebase and remove them).

Try it out if you like! if anything looks suspicious let me know, I'm happy to help.

Thanks! 
Can you confirm this works? I believe the `joiner` flow uses a space which doesn't seem to be supported by default in SublimeLinter. The `:` causes flow to throw an error when I try it on the cmd.