This change refreshes the updated version of Azure SDK
for Go that has the latest changes.

I manually vendored the new SDK (github.com/Azure/azure-sdk-for-go)
and I removed `management/` `core/` packages manually simply because
they're not used here and they have a fork of `net/http` and `crypto/tls`
for a particular reason. It was introducing a 44k SLOC change otherwise...

This also undoes the `include_azure` flag (actually Steven removed the
driver from imports but forgot to add the build flag apparently, so the
flag wasn't really including azure. 😄

 ). This also must be obsolete
now.

Fixes #620, #175.
Signed-off-by: Ahmet Alp Balkan <ahmetalpbalkan@gmail.com>