Fix #53 by removing python 2.7.6 from TravisCI builds

Author: seratch

.gitignore

@@ -12,3 +12,4 @@ tests/.cache
 .coverage
 .cache
 .DS_Store
+.vscode/

.travis.yml

@@ -1,8 +1,6 @@
-sudo: false
 dist: trusty
 language: python
 python:
-  - "2.7.6"
   - "2.7"
   - "3.4"
   - "3.5"
@@ -15,4 +13,4 @@ script:
   - flake8 slackeventsapi
   - py.test --cov-report= --cov=slackeventsapi tests
 after_success:
-  - codecov -e $TRAVIS_PYTHON_VERSION
+  - codecov -e $TRAVIS_PYTHON_VERSION