Support vim using the language server

[gaocegege]

Do a feasibility research to investigate if we could use the language server to support linting in vim.

See https://github.com/coala/coala-vs-code/issues/3#issuecomment-377661078

/assign @li-boxuan

[li-boxuan]

I've created a repository here: https://github.com/li-boxuan/coala-LSP-clients/tree/master/vim

This plugin won't work until this issue is solved: https://github.com/coala/coala-vs-code/issues/37

[gaocegege]

#37 is solved and it is not blocked anymore.