Rewrite liblog into a logging facade

See issue rust-lang#3 for background.

Closes rust-lang#3
Closes rust-lang#7
Closes rust-lang#11

Cargo.toml

@@ -9,8 +9,5 @@ repository = "https://github.com/rust-lang/log"
 documentation = "http://doc.rust-lang.org/log"
 homepage = "https://github.com/rust-lang/log"
 description = """
-Logging macros and infrastructure for Rust
+A lightweight logging facade for Rust
 """
-
-[dependencies]
-regex = "0.1"

README.md

@@ -1,23 +1,33 @@
 log
 ===
 
-A Rust library for application logging via debug/info/warn/error macros
+A Rust library providing a lightweight logging *facade*.
 
 [![Build Status](https://travis-ci.org/rust-lang/log.svg?branch=master)](https://travis-ci.org/rust-lang/log)
 
 [Documentation](http://doc.rust-lang.org/log)
 
+A logging facade provides a single logging API that abstracts over the actual
+logging implementation. Libraries can use the logging API provided by this
+crate, and the consumer of those libraries can choose the logging
+implementation that is most suitable for its use case.
+
+Libraries should simply depend on the `log` crate, using the various logging
+macros as they like. Applications should choose a logging implementation that
+will process all logging messages.
+
 ## Usage
 
 Add this to your `Cargo.toml`:
 
 ```toml
 [dependencies]
-log = "0.1.0"
+log = "0.2"
 ```
 
 and this to your crate root:
 
 ```rust
+#[macro_use]
 extern crate log;
 ```