let TODOs through linting, but warn about them

tox.ini

@@ -61,7 +61,7 @@ deps =
     {[base]deps}
 commands =
     flake8
-    - flake8 --disable-noqa --select=E,W,F,C,D,A,G,B,I,T,DUO
+    - flake8 --disable-noqa --ignore= --select=E,W,F,C,D,A,G,B,I,T,DUO
 
 [coverage:paths]
 source =
@@ -80,6 +80,7 @@ exclude =
     versioneer.py
     _version.py
     instance/
+ignore = T101
 max-complexity = 10
 max-line-length = 120