Add a configuration variable for greedy cask (fix #401)

src/config.rs

@@ -51,6 +51,11 @@ pub enum Step {
     Tmux,
 }
 
+#[derive(Deserialize, Default, Debug)]
+pub struct Brew {
+    greedy_cask: Option<bool>,
+}
+
 #[derive(Deserialize, Default, Debug)]
 pub struct Composer {
     self_update: Option<bool>,
@@ -79,6 +84,7 @@ pub struct ConfigFile {
     accept_all_windows_updates: Option<bool>,
     only: Option<Vec<Step>>,
     composer: Option<Composer>,
+    brew: Option<Brew>,
 }
 
 impl ConfigFile {
@@ -366,6 +372,15 @@ impl Config {
         self.config_file.accept_all_windows_updates.unwrap_or(true)
     }
 
+    /// Whether Brew cask should be greedy
+    pub fn brew_cask_greedy(&self) -> bool {
+        self.config_file
+            .brew
+            .as_ref()
+            .and_then(|c| c.greedy_cask)
+            .unwrap_or(false)
+    }
+
     /// Whether Composer should update itself
     pub fn composer_self_update(&self) -> bool {
         self.config_file