v5.3.1 breaks compatibility with Node 4.x

[prebuild]

v5.3.1 breaks compatibility with Node 4.x

[vweevers]

Pinning those, especially tar-fs, also means we lose bugfixes (in transitive dependencies). That said, I understand the need, and suggest we revisit this if and when we merge bugfixes or features here that are also important to node-snappy. Unless that's already true - see changes since 5.3.1.

[vweevers]

It's not completely unexpected, as we dropped 4 with a major bump and npm should warn about it:

prebuild-install/package.json

Lines 66 to 68 in 84e610b

	"engines": {
	"node": ">=6"
	}

I can't find it just now but there's also a related issue on one of the prebuild modules regarding node 6 support. We need to take some time to (re)consider our LTS policy. Will take your suggestion into consideration.

[emadum]

That definitely makes sense, and I don't think those updates matter for node-snappy. That said, I do think it would be helpful to keep 5.x working for node 4, and put those dependency upgrades into a 6.0 release. If there are modules other than node-snappy with a ^(>=5, <5.3.1) dependency, they will break unexpectedly in node 4.