Add pre_sudo option (#219)

* Add `pre_sudo` option

src/config.rs

@@ -269,6 +269,7 @@ pub struct Vim {
 #[serde(deny_unknown_fields)]
 /// Configuration file
 pub struct ConfigFile {
+    pre_sudo: Option<bool>,
     pre_commands: Option<Commands>,
     post_commands: Option<Commands>,
     commands: Option<Commands>,
@@ -947,6 +948,12 @@ impl Config {
             .unwrap_or(false)
     }
 
+    /// If `true`, `sudo` should be called after `pre_commands` in order to elevate at the
+    /// start of the session (and not in the middle).
+    pub fn pre_sudo(&self) -> bool {
+        self.config_file.pre_sudo.unwrap_or(false)
+    }
+
     #[cfg(target_os = "linux")]
     pub fn npm_use_sudo(&self) -> bool {
         self.config_file