Add Alibaba Cloud ECI Provider

Alibaba Cloud ECI(Elastic Container Instance) is a service that allow you
run containers without having to manage servers or clusters.

This commit add ECI provider for virtual kubelet, connects ECI with
kubernetes cluster.

Signed-off-by: xianwei.zw <xianwei.zw@alibaba-inc.com>
Signed-off-by: shidao.ytt <shidao.ytt@alibaba-inc.com>

providers/alicloud/config.go

@@ -0,0 +1,51 @@
+package alicloud
+
+import (
+	"io"
+
+	"github.com/BurntSushi/toml"
+	"github.com/virtual-kubelet/virtual-kubelet/providers"
+)
+
+type providerConfig struct {
+	Region          string
+	OperatingSystem string
+	CPU             string
+	Memory          string
+	Pods            string
+	VSwitch         string
+	SecureGroup     string
+}
+
+func (p *ECIProvider) loadConfig(r io.Reader) error {
+	var config providerConfig
+	if _, err := toml.DecodeReader(r, &config); err != nil {
+		return err
+	}
+
+	p.region = config.Region
+	if p.region == "" {
+		p.region = "cn-hangzhou"
+	}
+
+	p.vSwitch = config.VSwitch
+	p.secureGroup = config.SecureGroup
+
+	p.cpu = config.CPU
+	if p.cpu == "" {
+		p.cpu = "20"
+	}
+	p.memory = config.Memory
+	if p.memory == "" {
+		p.memory = "100Gi"
+	}
+	p.pods = config.Pods
+	if p.pods == "" {
+		p.pods = "20"
+	}
+	p.operatingSystem = config.OperatingSystem
+	if p.operatingSystem == "" {
+		p.operatingSystem = providers.OperatingSystemLinux
+	}
+	return nil
+}