Support string values for endpoint in JS client

[oubiwann]

This currently doesn't work:

var client = cmr.client.search.create_client({"endpoint": "local"});

Which means that the JS client can only run against prod right now ...

[axocomm]

Have you observed this happening with the token option as well? That's also being ignored on my end.

Looks like this could be as simple as options being passed around as an Object when coming from JavaScript. The function returned by create-service-client-constructor retrieves the endpoint and token with those two get-default-* functions which both accept options. Unfortunately, at this point, options is an Object and those values both end up being defaulted/nil.

I see this is handled to some degree in the ClojureScript version of base-impl/create-options wherein js->clj is called to convert options to a map before making it into a CMRClientOptions record.

If that sounds like it could be the issue, I'm wondering if you had any thoughts on most cleanly implementing a fix. It doesn't look like options is being used anywhere on its own downstream from the function returned by create-service-client-constructor, so perhaps a similar mechanism to the transformation of http-options will do (just the js->clj part of course)? After trying something like this, endpoint and token are both successfully populated and fallback to defaults when not provided.