Consistent sync and async function names

Specifically all synchronous functions should be *Sync and all other functions should be async. Mixed usage would be deprecated, but not removed for backwards compatibility.

For example, we should deprecate crypto functions like crypto.randomBytes(length) in favor of crypto.randomBytesSync(length).

There is no request for additional functionality. PR welcomed?

Reference: nodejs/node-v0.x-archive#7030