refactor(Examples): corrects compiler warnings about names

Closes #204

examples/02_apps.rs

@@ -2,8 +2,8 @@ extern crate clap;
 
 use clap::{App};
 
+#[allow(unused_variables)]
 fn main() {
-
     // Apps describe the top level application
     //
     // You create an App and set various options on that App using the "builder pattern"

examples/03_args.rs

@@ -2,8 +2,8 @@ extern crate clap;
 
 use clap::{App, Arg};
 
+#[allow(unused_variables)]
 fn main() {
-
     // Args describe a possible valid argument which may be supplied by the user at runtime. There
     // are three different types of arguments (flags, options, and positional) as well as a fourth
     // special type of argument, called SubCommands (which will be discussed separately).

examples/09_auto_version.rs

@@ -3,6 +3,7 @@ extern crate clap;
 
 use clap::App;
 
+#[allow(unused_variables)]
 fn main() {
     // You can have clap pull the application version directly from your Cargo.toml starting with
     // clap v0.4.14 on crates.io (or master#a81f915 on github). Using Rust's env! macro like this:

examples/10_default_values.rs

@@ -2,6 +2,7 @@ extern crate clap;
 
 use clap::{App, Arg};
 
+#[allow(unused_variables)]
 fn main() {
     // You can get a "default value" like feature by using Option<T>'s .unwrap_or() method
     //

examples/15_custom_validator.rs

@@ -2,6 +2,7 @@ extern crate clap;
 
 use clap::{App, Arg};
 
+#[allow(unused_variables)]
 fn main() {
     // You can define a function (or a closure) to use as a validator to argument values. The
     // function must accept a String and return Result<(), String> where Err(String) is the message

examples/16_app_settings.rs

@@ -2,6 +2,7 @@ extern crate clap;
 
 use clap::{App, AppSettings, SubCommand};
 
+#[allow(unused_variables)]
 fn main() {
     // You can use AppSettings to change the application level behavior of clap. .setting() function
     // of App struct takes AppSettings enum as argument. There is also .settings() function which

src/tests.rs

@@ -1,4 +1,4 @@
-use super::{App, Arg, SubCommand, AppSettings};
+use super::{App, Arg, SubCommand};
 use std::collections::HashSet;
 use std::vec::Vec;