Replace minio-go with aws-sdk-go for s3-compatible log backend (#670)

* Logs should support specifying region when using S3-compatible object store

* Use aws-sdk-go client for s3 backed logstore

* fixes vendor with aws-sdk-go dependencies

vendor/github.com/aws/aws-sdk-go/service/s3/s3crypto/padder.go

@@ -0,0 +1,35 @@
+package s3crypto
+
+// Padder handles padding of crypto data
+type Padder interface {
+	// Pad will pad the byte array.
+	// The second parameter is NOT how many
+	// bytes to pad by, but how many bytes
+	// have been read prior to the padding.
+	// This allows for streamable padding.
+	Pad([]byte, int) ([]byte, error)
+	// Unpad will unpad the byte bytes. Unpad
+	// methods must be constant time.
+	Unpad([]byte) ([]byte, error)
+	// Name returns the name of the padder.
+	// This is used when decrypting on
+	// instantiating new padders.
+	Name() string
+}
+
+// NoPadder does not pad anything
+var NoPadder = Padder(noPadder{})
+
+type noPadder struct{}
+
+func (padder noPadder) Pad(b []byte, n int) ([]byte, error) {
+	return b, nil
+}
+
+func (padder noPadder) Unpad(b []byte) ([]byte, error) {
+	return b, nil
+}
+
+func (padder noPadder) Name() string {
+	return "NoPadding"
+}