Test v2.x branch

[mhoeger]

This change adds v2,x as a branch to test. v2.x branch currently (see changes here):

• removes Node.js v8
• changes worker version to 2.0.0
• introduces "v2Compatible" flag which reverts everything [breaking]
• [breaking] does not duplicate http payload in context.bindingData
• [breaking] fixes HTTP output through context.done(null, res) and $return is not handled correctly #228 (handles http output correctly on context.(null, { body: "hello" });

TODO:

• remove Node.js v10 support?
  • potentially leverage Node.js v12 features
• [breaking] fix camelCase of timer trigger object: camelCase Timer Trigger object #188
  • potentially add to .proto
• [breaking] consider removing context.req and context.res objects: Remove duplication / improve organization on "context" properties #204
• [breaking] in host and worker, make sure http payload "as raw" as possible
• explore options for bugs with protobuf.js and windows (Issue 1303, Issue 1275)
  • protoc or just default Linux and accept Windows bugs? Probably document windows bugs

[mhoeger]

@ColbyTresness and @pragnagopa and @fabiocav

[ColbyTresness]

We decided with @fabiocav not to remove Node 10 here. Other than that looks good