Auto merge of #2081 - vi:cargo_init, r=alexcrichton

Implement `cargo init` command and appropriate tests ( #21).

Features:
* Working like `cargo new` if there are no files in current directory
* Auto-detection of `--bin`
* Auto-detection of already existing VSC and appending to respecive ignore file
* Appending of appropriate `[lib]` or `[[bin]]` section to `Cargo.toml` in case of some non-standard source locations

Concerns:
* I'm not experienced in Rust + lazy => code looks poorer compared to the rest Cargo code
* The test don't cover 100% of functions
* Project consisting of both binary and library is not handled
* Many deviations from [previously proposed algorithm](#2008 (comment))

src/bin/cargo.rs

@@ -69,6 +69,7 @@ macro_rules! each_subcommand{
         $mac!(generate_lockfile);
         $mac!(git_checkout);
         $mac!(help);
+        $mac!(init);
         $mac!(install);
         $mac!(locate_project);
         $mac!(login);

src/bin/init.rs

@@ -0,0 +1,53 @@
+use std::env;
+
+use cargo::ops;
+use cargo::util::{CliResult, Config};
+
+#[derive(RustcDecodable)]
+struct Options {
+    flag_verbose: bool,
+    flag_quiet: bool,
+    flag_color: Option<String>,
+    flag_bin: bool,
+    arg_path: Option<String>,
+    flag_name: Option<String>,
+    flag_vcs: Option<ops::VersionControl>,
+}
+
+pub const USAGE: &'static str = "
+Create a new cargo package in current directory
+
+Usage:
+    cargo init [options] [<path>]
+    cargo init -h | --help
+
+Options:
+    -h, --help          Print this message
+    --vcs VCS           Initialize a new repository for the given version
+                        control system (git or hg) or do not initialize any version
+                        control at all (none) overriding a global configuration.
+    --bin               Use a binary instead of a library template
+    --name NAME         Set the resulting package name
+    -v, --verbose       Use verbose output
+    -q, --quiet         No output printed to stdout
+    --color WHEN        Coloring: auto, always, never
+";
+
+pub fn execute(options: Options, config: &Config) -> CliResult<Option<()>> {
+    debug!("executing; cmd=cargo-init; args={:?}", env::args().collect::<Vec<_>>());
+    try!(config.shell().set_verbosity(options.flag_verbose, options.flag_quiet));
+    try!(config.shell().set_color_config(options.flag_color.as_ref().map(|s| &s[..])));
+
+    let Options { flag_bin, arg_path, flag_name, flag_vcs, .. } = options;
+
+    let opts = ops::NewOptions {
+        version_control: flag_vcs,
+        bin: flag_bin,
+        path: &arg_path.unwrap_or(format!(".")),
+        name: flag_name.as_ref().map(|s| s.as_ref()),
+    };
+
+    try!(ops::init(opts, config));
+    Ok(None)
+}
+