Add CommandExt trait (#146)

* Color CI output

* Improve `CommandExt`

* Add comments explaining `#[allow]`s

* Remove useless `dead_code` annotation

* Improve error messages

* Print errors when running a shell errors

* fixup! Remove useless `dead_code` annotation

src/steps/os/dragonfly.rs

@@ -11,7 +11,7 @@ pub fn upgrade_packages(sudo: Option<&PathBuf>, run_type: RunType) -> Result<()>
     run_type
         .execute(sudo)
         .args(&["/usr/local/sbin/pkg", "upgrade"])
-        .check_run()
+        .status_checked()
 }
 
 pub fn audit_packages(sudo: &Option<PathBuf>) -> Result<()> {
@@ -19,8 +19,7 @@ pub fn audit_packages(sudo: &Option<PathBuf>) -> Result<()> {
         println!();
         Command::new(sudo)
             .args(&["/usr/local/sbin/pkg", "audit", "-Fr"])
-            .spawn()?
-            .wait()?;
+            .status_checked()?;
     }
     Ok(())
 }