Upgrade go-amqp to v1.0.1

This PR upgrades the direct dependencies of iothub, with a lot of emphasis on the go-amqp changes in v1.0.0.

Upgrade github.com/eclipse/paho.mqtt.golang from v1.3.5 to v1.4.2.
- The are no functional changes which should be relevant here, only a license change.
Upgrade github.com/Azure/go-amqp from v0.18.1 to v1.0.1.
- The Dial function now takes a context, so I've introduced *Context functions which allow context propagation and marked the existing ones as deprecated.
- Receive now takes non-optional ReceiveOptions, but they are empty in this release.
- Send now takes non-optional SendOptions, and there is Settled option which has been added, but I've left it unspecified for now.
- @alexg-axis can you take a look if the changes look good to you, and perhaps test them ?

amenzhinsky / iothub