Enhanced exceptions

This commit also contains:
- eslint + jscs break the process as they should if there is an error
- test should fail if no error is thrown on each t.throws tests
- throwing the same error keep the original stack trace

The helper I'm using only enhance exceptions that can be thrown & do not throw a new exception.

Note: I'm making a PR because I don't have npm rights for now :)
lol sorry I completly commit some shit here. I was working on old try{}catch this morning https://github.com/MoOx/postcss-message-helpers/blob/fd4a7408f0a82b550b7cf84ac6e3071562e56cb9/test/index.js#L23-L57
I will remove that asap.