Changed NymConfig to take optional id for some of its method

common/config/src/lib.rs

@@ -12,12 +12,16 @@ pub trait NymConfig: Default + Serialize + DeserializeOwned {
     fn default_root_directory() -> PathBuf;
 
     // default, most probable, implementations; can be easily overridden where required
-    fn default_config_directory() -> PathBuf {
-        Self::default_root_directory().join("config")
+    fn default_config_directory(id: Option<&str>) -> PathBuf {
+        Self::default_root_directory()
+            .join(id.unwrap_or(""))
+            .join("config")
     }
 
-    fn default_data_directory() -> PathBuf {
-        Self::default_root_directory().join("data")
+    fn default_data_directory(id: Option<&str>) -> PathBuf {
+        Self::default_root_directory()
+            .join(id.unwrap_or(""))
+            .join("data")
     }
 
     fn root_directory(&self) -> PathBuf;
@@ -35,9 +39,9 @@ pub trait NymConfig: Default + Serialize + DeserializeOwned {
         )
     }
 
-    fn load_from_file(custom_location: Option<PathBuf>) -> io::Result<Self> {
+    fn load_from_file(custom_location: Option<PathBuf>, id: Option<&str>) -> io::Result<Self> {
         let config_contents = fs::read_to_string(
-            custom_location.unwrap_or(Self::default_config_directory().join("config.toml")),
+            custom_location.unwrap_or(Self::default_config_directory(id).join("config.toml")),
         )?;
 
         let parsing_result = toml::from_str(&config_contents)