encode uri before send

[zombie-king]

fix for: https://sourceforge.net/p/davmail/mailman/davmail-users/thread/c2c50f73-b87e-f5e9-1f2f-eb28c9da4f04%40free.fr/
duo authentication is broken due to pipe character. Encoding uri fixes that issue. I think only query string should be encoded but the whole relative path is encoded in that patch.

[mguessan]

This patch is against old HttpClient 3 code, can you please confirm if it's still relevant with HC4 ?

Impacted code would be arount line 302:

exchangeUri = postLogonMethod(httpClient, postRequest, password).getURI();