* Specify type before parameter name
Various JSDoc `@param` entries were specified as `name {type}` rather
than `{type} name`.
A couple of `@return` entries have been given types as well.
* Use JSDoc optional syntax rather than Closure syntax
* Use @returns rather than @return
* Use consistent built-in type capitalization
Primitive types are lower-case, and Object is upper-case.
* Separate param/return description with a dash
* Add network store for testing
An alternative persistent state store has been created for use with e2e
tests. Instead of reading state from disk, it tries to load state from
a local fixture server running on port `12345` and serving state from
the path `/state.json`, and returns a blank state otherwise.
* Add e2e test fixture server
A fixture server has been added for serving background state, which the
background will read upon startup as part of restoring persisted state.
The `signature-request` e2e test has been updated to use a fixture to
bypass the registration step. The fixture used (`imported-account`) was
generated by pausing midway through that test run
