Improve package metadata

Author: tailhook

Cargo.toml

@@ -5,7 +5,8 @@ description = "Powerful command-line argument parsing library"
 license = "MIT"
 readme = "README.rst"
 keywords = ["command-line", "cli", "command", "argument"]
+categories = ["command-line-interface"]
 homepage = "http://github.com/tailhook/rust-argparse"
 version = "0.2.1"
-authors = ["paul@colomiets.name"]
+authors = ["Paul Colomiets <paul@colomiets.name>"]