Add support for spec-relative module ids. Any ids that flow through a
context's module loader--including module, create, or anything loaded
via the plugin wire.loadModule API--which are relative (start with
'./' or '../'), will be treated as relative to the spec's module id.
If the spec has no module id (e.g. programmtically wiring an object
literal), the parent context's loader will be used, which itself may
have relative-id behavior.

Add initial support for relative module ids in wire specs. Regression tests pass, needs unit tests

Split relativeId to its own module

Add relativeId tests using gent

Add spec-relative module id tests for amd. Found errors, fixed, win. Node tests coming soon.

Add unit tests for spec-relative moduleIds in node. Banish more done()-based tests in favor of promise-returning. Finally rename all tests to *-test.js