Introspect Remote Schemas with options

[SVilgelm]

Add new IntrospectRemoteSchemasWithOptions function to keep the IntrospectRemoteSchemas function backward compatible.
The new function accepts the list of urls and the Introspect Options.

Add the Introspect Options:

• IntrospectWithMiddlewares to use custom network middlewares
• IntrospectWithHTTPClient to use a custom http client
• IntrospectWithContext to use a custom global context

Update the IntrospectAPI function to accept the introspect options.

[SVilgelm]

@AlecAivazis Hi, Could you please review this PR?
I see a question about the passing middleware was raised several times and I had to implement own version of IntrospectRemoteSchemas function to pass the middlewares and use a custom http client (we need to use the custom certificates). So I think it will be better to have such functionality right here

[SVilgelm]

@AlecAivazis would you be able to review this PR?

[AlecAivazis]

Hey @SVilgelm! Thanks for being patient :) just a quick comment on the proposed API but we should be able to get this in quickly

[SVilgelm]

Hey @SVilgelm! Thanks for being patient :) just a quick comment on the proposed API but we should be able to get this in quickly

no worries, thank you for you response

[AlecAivazis]

Im going to merge this in now even tho travis is complaining. I'll get to the bottom of the issue once this is released