[AliCloud] Add init container (#382)

* clean up eci sdk code

remove unnecessary code

* add init containers support

providers/alicloud/eci/struct_environment_var.go

@@ -17,6 +17,6 @@ package eci
 
 // EnvironmentVar is a nested struct in eci response
 type EnvironmentVar struct {
-	Key   string `json:"Key" xml:"Key" position:"Query" name:"Key"`
-	Value string `json:"Value" xml:"Value" position:"Query" name:"Value"`
+	Key   string `name:"Key"`
+	Value string `name:"Value"`
 }