requirements: change pylint to version 2.2.2

.travis.yml

@@ -4,6 +4,7 @@ before_install:
   - sudo apt-get update
   - sudo apt-get install python3
   - sudo apt-get install python3-pip
+  - sudo python3 -m pip install --upgrade pip
 # command to install dependencies
 install:
   - python3 -m pip install -r requirements.txt --user

pylint.rc

@@ -7,4 +7,5 @@ disable=too-few-public-methods,
         too-many-locals,
         no-init,
         len-as-condition,
-        too-many-instance-attributes
+        too-many-instance-attributes,
+        invalid-name

requirements.txt

@@ -1,4 +1,4 @@
 eventemitter==0.2.0
 asyncio==3.4.3
 websockets==7.0
-pylint==1.8.3
+pylint==2.2.2