Improve https get diagnostics, add verbose option

* Implement a logging client and activate it using verbose parameter or option
   in checker and aggregator.

Co-authored-by: Sascha L. Teichmann <sascha.teichmann@intevation.de>

docs/csaf_aggregator.md

@@ -66,6 +66,7 @@ openpgp_url   // URL where the OpenPGP public key part can be found
 passphrase    // passphrase of the OpenPGP key
 lock_file     // path to lockfile, to stop other instances if one is not done
 interim_years // limiting the years for which interim documents are searched
+verbose       // print more diagnostic output, e.g. https request
 allow_single_provider // debugging option
 ```
 

docs/csaf_checker.md

@@ -12,10 +12,13 @@ Application Options:
       --client-cert=CERT-FILE    TLS client certificate file (PEM encoded data)
       --client-key=KEY-FILE      TLS client private key file (PEM encoded data)
       --version                  Display version of the binary
+  -v, --verbose                  Verbose output
+  -r, --rate=                    The average upper limit of https operations
+                                 per second
 
 Help Options:
   -h, --help                     Show this help message
 ```
 
 Usage example:
-` ./csaf_checker example.com -f html -o check-results.html`
+` ./csaf_checker example.com -f html --rate=5.3 -o check-results.html`