Move check for blacklisted names to pylint

Check for blacklisted names ‘l’, ‘O’, and ‘I’ with pylint instead of
pycodestyle, this allows to disable the check inline.

Change-Id: I765f0d62d541fe55125396ff55ee3597f8086987

pycodestyle

 [pycodestyle]
-ignore = W503,E501
+ignore = W503,E501,E741,E742,E743

pylintrc

@@ -109,7 +109,7 @@ evaluation=10.0 - ((float(5 * error + warning + refactor + convention) / stateme
 good-names=i,j,k,ex,Run,_
 
 # Bad variable names which should always be refused, separated by a comma
-bad-names=foo,bar,baz,toto,tutu,tata
+bad-names=foo,bar,baz,toto,tutu,tata,I,l,O
 
 # Colon-delimited sets of names that determine each other's naming style when
 # the name regexes allow several styles.