Add pylint configuration and instructions

pylint configuration file (.pylintrc) is added, and submission
instructions are updated to include pylint usage steps.

Deprecated pylint suppression (`disable-msg`) is updated in a few
modules to make it work properly with the latest version (0.26).

Change-Id: I4ec2ef318e23557a374ecdbf40fe12645766830c
diff --git a/command.py b/command.py
index 51c0cb4..d543e3a 100644
--- a/command.py
+++ b/command.py
@@ -147,7 +147,7 @@
     result.sort(key=_getpath)
     return result
 
-# pylint: disable-msg=W0223
+# pylint: disable=W0223
 # Pylint warns that the `InteractiveCommand` and `PagedCommand` classes do not
 # override method `Execute` which is abstract in `Command`.  Since that method
 # is always implemented in classes derived from `InteractiveCommand` and
@@ -166,7 +166,7 @@
   def WantPager(self, opt):
     return True
 
-# pylint: enable-msg=W0223
+# pylint: enable=W0223
 
 class MirrorSafeCommand(object):
   """Command permits itself to run within a mirror,