Bump version of logging crates and fix broken links in logging.md

Author: budziq

Cargo.toml

@@ -17,15 +17,15 @@ clap = "2.29"
 crossbeam = "0.3"
 csv = "1.0"
 data-encoding = "2.1.0"
-env_logger = "0.4"
+env_logger = "0.5"
 error-chain = "0.11"
 flate2 = "1.0"
 glob = "0.2"
 hyper = "0.11"
 image = "0.19"
 lazy_static = "1.0"
-log = "0.3"
-log4rs = "0.7"
+log = "0.4"
+log4rs = "0.8"
 memmap = "0.6"
 mime = "0.3"
 num = "0.1"
@@ -50,7 +50,7 @@ url = "1.6"
 walkdir = "2.0"
 
 [target.'cfg(target_os = "linux")'.dependencies]
-syslog = "3.3.0"
+syslog = "4.0"
 
 [build-dependencies]
 skeptic = "0.13"