proxifiedContainers.delete routine added and loosely tested

src/js/proxified-containers.js

@@ -146,5 +146,31 @@ proxifiedContainers = {
 
       return result;
     }
+  },
+
+  //Deletes the proxy information object for a specified cookieStoreId [useful for cleaning]
+  delete(cookieStoreId) {
+    return new Promise((resolve, reject) => {
+      // Assumes proxy is a properly formatted object
+      proxifiedContainers.retrieve().then((proxifiedContainersStore) => {
+        let index = proxifiedContainersStore.findIndex(i => i.cookieStoreId === cookieStoreId);
+
+        if (index === -1) {
+          reject({error: "not-found", message: `Container '${cookieStoreId}' not found.`});
+        } else {
+          delete proxifiedContainersStore[index];
+        }
+
+        browser.storage.local.set({
+          proxifiedContainersKey: proxifiedContainersStore
+        });
+
+        resolve();
+      }, (errorObj) => {
+        reject(errorObj);
+      }).catch((error) => {
+        throw error;
+      });
+    });
   }
 };