streamlined travis process and dependencies

.travis.yml

@@ -15,11 +15,10 @@ install:
   - sudo apt-get install rethinkdb
   - pip install -e .[test]
   - pip install codecov
-  - pip install flake8
 
 before_script:
-  - rethinkdb --daemon
   - flake8 --max-line-length 119 bigchaindb/
+  - rethinkdb --daemon
 
 script: py.test -n auto -s -v --cov=bigchaindb
 

setup.py

@@ -31,7 +31,7 @@ check_setuptools_features()
 tests_require = [
     'coverage',
     'pep8',
-    'pyflakes',
+    'flake8',
     'pylint',
     'pytest',
     'pytest-cov==2.2.1',