Upgrade pylint&astroid to a version that works with python3.7

1. Astroid and pylint are tightly coupled,so both versions should be specified for python3.7

2. A few rules are added to the ignore list in .pylintrc

Change-Id: Ice65c8fa94a2de2c0365ec5ab710d93675aacbb9

.pylintrc

@@ -44,8 +44,7 @@ symbols=no
 # --enable=similarities". If you want to run only the classes checker, but have
 # no Warning level messages displayed, use"--disable=all --enable=classes
 # --disable=W"
-disable=W,C,R,no-member
-
+disable=W,C,R,no-member,assignment-from-no-return,assignment-from-none
 
 [REPORTS]
 

lower-constraints.txt

@@ -1,5 +1,5 @@
 alabaster==0.7.10
-astroid==1.3.8
+astroid==1.6.5
 Babel==2.3.4
 cliff==2.8.0
 cmd2==0.8.0

test-requirements.txt

@@ -5,6 +5,10 @@ flake8<2.6.0,>=2.5.4 # MIT
 hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
 mock>=2.0.0 # BSD
-pylint==1.9.2 # GPLv2
+#pylint==1.9.2 # GPLv2
 stestr>=2.0.0 # Apache-2.0
 testtools>=2.2.0 # MIT
+astroid==1.6.5;python_version<"3.0" # LGPLv2.1
+astroid==2.1.0;python_version>="3.0" # LGPLv2.1
+pylint==1.9.2;python_version<"3.0" # GPLv2
+pylint==2.2.0;python_version>="3.0" # GPLv2