wsclient - if basic_header is not enabled, login as petascope admin user should be able to remove coverages from external

[Bang Pham Huu]

When user logged in as petascope admin user in WSClient and petascope is not enabled with basic header authentication, then, WSClient needs to send these admin credentials to petascope per each request to bypass the check if a write request can be requested from external IP address (default only localhost is allowed).