add humanfriendly (new granary dependency) and appengine_config hack for it

appengine_config.py

@@ -18,6 +18,16 @@ if os.environ.get('SERVER_SOFTWARE', '').startswith('Google App Engine/'):
   HOST = 'fed.brid.gy'
   HOST_URL = '%s://%s' % (SCHEME, HOST)
 
+# Stub out the multiprocessing module. it's not supported on App Engine
+# Standard, but humanfriendly uses it for some terminal animation thing that we
+# don't need.
+import sys
+from types import ModuleType
+
+class DummyProcessing(ModuleType):
+  pass
+sys.modules['multiprocessing'] = DummyProcessing
+
 # Make requests and urllib3 play nice with App Engine.
 # https://github.com/snarfed/bridgy/issues/396
 # http://stackoverflow.com/questions/34574740

requirements.freeze.txt

@@ -23,6 +23,7 @@ html2text==2019.8.11
 html5lib==1.0.1
 httplib2==0.14.0
 -e git+git@github.com:snarfed/httpsig.git@6f0ebfe00af39fb75d50c7a29f46da49e8190d70#egg=httpsig
+humanfriendly==4.18
 humanize==0.5.1
 idna==2.8
 Jinja2==2.10.3