Update ListFiles() to support write token, path, Files API v2. Protect against pollution of Networks()

[eponymous301]

• ListFiles() changes:
  • Add support for getting info from a draft using a writeToken
  • Add support for requesting a list from a subdirectory using path (return value will be recursive list)
  • Change URL to Files API version2
• Protect against tampering of networks var by having Networks() return a copy of the object rather than original
• Fix 'type coercion' warning (== vs ===) in UploadFileData()