Don't use https://api.parse.com/1 as default serverURL

[simonbengtsson]

The parse js sdk uses https://api.parse.com/1 as default serverURL for obvious reasons. However I can't think of a common use case for it in Parse Server and it might be confusing #356 #407 #477. This pull request simply overwrites the default url with en empty string if the user does not specify it.

When using queries in cloud code and forgetting to change the serverURL you currently get a ParseError { code: undefined, message: 'unauthorized' }. With this change you instead get a ParseError {code: 100, message: 'XMLHttpRequest failed: "Unable to connect to the Parse API"' }. This might only be a slight improvement, but it makes it possible to add a custom error message in the parse js sdk when no serverURL is found.

It might also be desirable to make serverURL a required property or adding a warning when it is not set?

[drew-gross]

Awesome, I think this will improve the usability of Parse Server quite a bit. I like your idea of making it required, though, I think that would be an even better experience. @gfosco is there any situation where you wouldn't care if serverURL isn't set? Maybe if you don't have cloud code? If thats the case we could require a serverURL only if any Cloud Code is also provided.

[flovilmart]

the Parse SDK need the serverURL, for any code running on the server whether it's Cloud Code or not.

[facebook-github-bot]

@simonbengtsson updated the pull request.

[gfosco]

I like this because at least it will fail, rather than incorrectly calling Parse. If users run in to problems here, we'll have to readdress how we enforce it.