Move logging config to main configuration file.

- Move the content of what was stored in log4rs.yml into the main config
  file, so that there is just one file to parse to get the complete
  configuration.
- Create the global switch `--home` to pass/overload the value for
  SEQUOIA_HOME in the configuration file.

src/cli/cli_args.rs

@@ -15,6 +15,13 @@ pub struct CliArgs {
     )]
     pub config: Option<String>,
 
+    #[clap(
+        long,
+        global = true,
+        help = "Certification store (SEQUOIA_HOME).",
+    )]
+    pub home: Option<String>,
+
     #[clap(subcommand)]
     pub subcommand: HuskSubcommands,
 }