switched out npm for yarn to manage node deps

README.md

@@ -2,6 +2,10 @@
 payment subscription REST api for customers:
 - FxA (Firefox Accounts)
 
+## Required Software
+- python3.7: requires python3.7 interpreter for creating virtual envionments for testing and running subhub
+- yarn (https://yarnpkg.com): package manager for node modules for setting up serverless for running and deploying subhub
+
 ## Important Environment Variables
 The CFG object is for accessing values either from the `subhub/.env` file and|or superceeded by env vars.
 A value that is known to be set or have a default can be accessed:

dodo.py

@@ -221,10 +221,11 @@ def check_reqs():
 
 def task_check():
     '''
-    checks: noroot, python3.7, awscli, json, yaml, black, reqs
+    checks: noroot, python3.7, yarn, awscli, json, yaml, black, reqs
     '''
     yield check_noroot()
     yield gen_prog_check('python3.7')
+    yield gen_prog_check('yarn')
     if not CFG('TRAVIS', None):
         yield gen_prog_check('awscli', 'aws')
     yield gen_file_check('json', json.load, '**/*.json')