Add Context to Saver Interface (#179)

* Adding context to storage.Saver parameters

* +`buffalo.Context` as first param in storage.Saver

Fixes #177

* Parallelizing Upload to Azure Blob Storage

Fixes #175

* Fixing import clausing

* go fmt ./...

* Populating default context

* CI: Echo files modified by gofmt check to stderr

Doing so allows users to see which files still need to be formatted.

* Upgrading Go, then go fmt ./...

* Addressing Feedback

* more responding to feedback

* Adding worker save Default Context

* Removing tracing, buffalo.Context usage in Storage interface

github.com/bketelsen/buffet relies on using a `buffalo.Context`
however, often a `storage.Saver` is invoked from a buffalo worker,
which has no buffalo.Context associated with it. Therefore, we had
two options: create a buffalo context for each worker's Job, or
remove the buffalo.Context dependency in the Saver interface.

* Fixing missed changes

* Review feedback

pkg/storage/minio/minio_test.go

@@ -1,12 +1,13 @@
 package minio
 
 import (
+	"context"
 	"io/ioutil"
 )
 
 func (d *MinioTests) TestGetSaveListRoundTrip() {
 	r := d.Require()
-	r.NoError(d.storage.Save(module, version, mod, zip, info))
+	r.NoError(d.storage.Save(context.Background(), module, version, mod, zip, info))
 	listedVersions, err := d.storage.List(module)
 	r.NoError(err)
 	r.Equal(1, len(listedVersions))