Avoid caret during installation

[mcollina]

For some context, I would like mysql to use the latest readable-stream: mysqljs/mysql#1677

[calvinmetcalf]

dependencies of dependencies are also an issue, which is why I did it this way

[mcollina]

Updated, this should work also on older versions of NPM.

[mcollina]

@calvinmetcalf yes. But it might allow the mysql module to upgrade to v2. We don't expect buffer-shims to change at any point in time either.

[AdriVanHoudt]

I don't see the node 0.6 travis change in the files changed as stated in the title or is that just me?

[mcollina]

I updated the title. We cannot really run our tests on Node v0.6.
Depending using ~ simplify backporting to old NPM versions. The tests passes, but our own test dependencies cannot be installed there anymore.