2.0 - Feature - Request Context

[calvincestari]

For the next major release of the network module we should take into consideration the following to improve users' ability to control the underlying URLRequest.

• Context of request timeout; session vs. request. Should extend to other request properties.
• What you can control and what you can't, i.e.: letting users' set the session timeout (global) but not the per-request timeout (this was the behaviour until 1.19.0)
• What we should do for 2.0?
• RequestContext protocol; look at the protocol based approach offered in feature: Configure URLRequest timeout interval apollo-ios-dev#618.