Upgrade dev dependencies in package.json

[rjmunro]

But stick with a 2.x.x version of JSCS as upgrading to 3.x.x broke things.

[coveralls]

Coverage decreased (-1.01%) to 92.929% when pulling 5f45ed7 on rjmunro:upgrade-deps into aaf26a1 on tarmolov:master.

[coveralls]

Coverage decreased (-1.01%) to 92.929% when pulling 5f45ed7 on rjmunro:upgrade-deps into aaf26a1 on tarmolov:master.

[coveralls]

Coverage increased (+1.9%) to 97.895% when pulling a09af18 on rjmunro:upgrade-deps into e83af69 on tarmolov:master.

[tarmolov]

I think it's better to replace jsint + jscs with eslint.
https://github.com/ymaps/codestyle/tree/master/packages/eslint-config-loris — here is the right base config for it.

Would you like to make this replacement in this pr?

[rjmunro]

@tarmolov I can look into that, yes. What do you think of dropping support for node 0.x? So we would only support node 4 and above? It means we can drop some older code and use e.g. execSync and have to worry about accessSync versus existsSync.

[tarmolov]

I think 4 can be dropped as well according to https://github.com/nodejs/Release#release-schedule.
After this changes it's better to up git-hooks major version because we break backward compatibility.

[rjmunro]

I've upgraded to node v5 and removed some code only necessary on older versions. I've had a go at moving to eslint, but I've decided that should be a separate PR (#59) as I'm not sure how to fix the errors it is throwing.

It would be great if this could be merged, then I can rebase #57 and #58 and therefore fix #48. This would mean that my project would start validating even when it is a submodule, which will save me a lot of frustration.