Add timeout configuration for requests

#### Support plan

* *is this issue currently blocking your project?* (yes/no): no
* *is this issue affecting a production system?* (yes/no): yes

#### Context

* *node version*: 12
* *module version*: 12.2.0
* *environment* (e.g. node, browser, native): node
* *used with* (e.g. hapi application, another framework, standalone, ...): hapi application
* *any other relevant information*:

#### What problem are you trying to solve?

We saw an issue recently where our authentication requests (specifically the token call) timed out after 2 minutes, which ended up increasing our response times dramatically. It woul be nice to be able to configure a timeout ourselves to allow requests to fail faster, since we don't expect them to take anywhere near that long.

#### Do you have a new or modified API suggestion to solve the problem?
Add a `timeout` option to the provider options