Use log verbosity level from configration

Following #440 (comment).

Author: romanz

Diff for: server.sh

@@ -10,7 +10,7 @@ shift
 
 DB=./db2  # $HOME/tmp/electrs_db/mainnet_zstd
 CMD="target/release/electrs --network $NETWORK --db-dir $DB --daemon-dir $HOME/.bitcoin"
-export RUST_LOG=${RUST_LOG-info}
+# export RUST_LOG=${RUST_LOG-info}
 $CMD $*
 
 # use SIGINT to quit

Diff for: src/config.rs

@@ -267,6 +267,12 @@ impl Config {
             }
         });
 
+        let level = match config.verbose {
+            0 => log::LevelFilter::Info,
+            1 => log::LevelFilter::Debug,
+            _ => log::LevelFilter::Trace,
+        };
+
         let config = Config {
             network: config.network,
             db_path: config.db_dir,
@@ -286,6 +292,7 @@ impl Config {
         env_logger::Builder::from_default_env()
             .default_format()
             .format_timestamp_millis()
+            .filter_level(level)
             .init();
         config
     }