backups: add setup/teardown

1. add setup, teardown hooks
2. move the managed mount setup and teardown to filesystem backend
3. remove this vague storage.js

we should convert storageApi into a real object, so we don't have to
keep passing apiConfig around

src/storage/interface.js

@@ -25,6 +25,10 @@ exports = module.exports = {
     remove,
     removeDir,
 
+    setup,
+    teardown,
+    cleanup,
+
     testConfig,
     removePrivateFields,
     injectPrivateFields
@@ -124,3 +128,19 @@ async function testConfig(apiConfig) {
 
     throw new BoxError(BoxError.NOT_IMPLEMENTED, 'testConfig is not implemented');
 }
+
+async function setup(apiConfig) {
+    assert.strictEqual(typeof apiConfig, 'object');
+
+    // Result: none - first callback argument error if config does not pass the test
+
+    throw new BoxError(BoxError.NOT_IMPLEMENTED, 'setup is not implemented');
+}
+
+async function teardown(apiConfig) {
+    assert.strictEqual(typeof apiConfig, 'object');
+
+    // Result: none - first callback argument error if config does not pass the test
+
+    throw new BoxError(BoxError.NOT_IMPLEMENTED, 'teardown is not implemented');
+}