Make VM service id handling JSON-RPC 2 compliant.

CHANGELOG.md

Index: CHANGELOG.md
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 [package spec proposal]: https://github.com/lrhn/dep-pkgspec
 
+### VM Service Protocol Changes
+
+* The service protocol now includes a `"jsonrpc"` property in its responses, as
+  opposed to `"json-rpc"`.
+
+* The service protocol now properly handles requests with non-string ids.
+  Numeric ids are no longer converted to strings, and null ids now don't produce
+  a response.
+
 ## 1.11.2
 
 ### Core library changes