Fix Azure deploy

- Fix handling of special characters in the Azure deployment config
  by quoting the VPN parameters
- Fixes hwdsl2#644. Thanks @turbozapekanka for the report!

azure/README-zh.md

@@ -12,6 +12,8 @@
  - Operating System Image （操作系统镜像，Debian 9 或 Ubuntu 16.04 LTS）
  - Virtual Machine Size （虚拟机大小，默认值： Standard_B1s）
 
+**注：** \*不要\* 在值中使用这些字符： `\ " '`
+
 请单击以下按钮开始：
 
 <a href="https://portal.azure.com/#create/Microsoft.Template/uri/https%3A%2F%2Fraw.githubusercontent.com%2Fhwdsl2%2Fsetup-ipsec-vpn%2Fmaster%2Fazure%2Fazuredeploy.json" target="_blank">

azure/README.md

@@ -12,6 +12,8 @@ Customizable with the following options:
  - Operating System Image (Debian 9 or Ubuntu 16.04 LTS)
  - Virtual Machine Size (Default: Standard_B1s)
 
+**Note:** DO NOT use these special characters within values: `\ " '`
+
 Press this button to start:
 
 <a href="https://portal.azure.com/#create/Microsoft.Template/uri/https%3A%2F%2Fraw.githubusercontent.com%2Fhwdsl2%2Fsetup-ipsec-vpn%2Fmaster%2Fazure%2Fazuredeploy.json" target="_blank">

azure/azuredeploy.json

@@ -47,6 +47,7 @@
  }
  },
  "variables": {
+ "quote": "'",
  "location": "[resourceGroup().location]",
  "vmName": "vpnserver",
  "virtualNetworkName": "vpnVnet",
@@ -71,7 +72,7 @@
  "version": "latest"
  },
  "installScriptURL": "https://raw.githubusercontent.com/hwdsl2/setup-ipsec-vpn/master/azure/install.sh",
- "installCommand": "[concat('sh install.sh ', parameters('preSharedKey'), ' ', parameters('username'), ' ', parameters('password'))]"
+ "installCommand": "[concat('sh install.sh ', variables('quote'), parameters('preSharedKey'), variables('quote'), ' ', variables('quote'), parameters('username'), variables('quote'), ' ', variables('quote'), parameters('password'), variables('quote'))]"
  },
  "resources": [
  {