vim-polyglot as syntax plugin

[sheerun]

Hey, I thought I'd suggest to use my plugin for syntaxes: https://github.com/sheerun/vim-polyglot

* It won't affect your startup time, as scripts are loaded only on demand*.
* It installs and updates 70+ times faster than 70+ packages it consist of.
* Solid syntax and indentation support. Only the best language packs.
* All unnecessary files are ignored (like enormous documentation from php support).
* No support for esoteric languages, only most popular ones (modern too, like slim).
* Each build is tested by automated vimrunner script on CI. See spec directory.

It is maintained for 3+ years and it doesn't seem to change in near future.