Check http status when request stable version

[kaduartur]

What happened:

• If the stable version server is down, the stable-version-cache.json going to update with an error message.
  For example:

{
  "stableVersion": "<?xml version=\"1.0\" encoding=\"UTF-8\"?><Error><Code>NoSuchKey</Code><Message>The specified key does not exist.</Message><Key>stable-legacyddf.txt</Key><RequestId>D223B393B6FDC09F</RequestId><HostId>HLq0ZVARrOAWLXtUAEwO2LpM/7A4dAyYDXRNWgMkiB3Ov/QGduX8RWPHs+LhYPwOMODW77OXEZ0=</HostId></Error>",
  "expiresAt": 1596848411
}

What you expected to happen:

• I expect to keep the old version in case an error occurs

How to reproduce it (as minimally and precisely as possible):

• You can edit the StableVersionUrl variable inside rit code and Unix timestamp inside stable-version-cache.json to get this error.

Anything else we need to know?:

Environment:

• Ritchie version (use rit --version): 1.0.0 and 2.0.2
• Operating System: Mx-linux
• Network plugin / Tool and version (if this is a network-related / tool bug):
• Others: