install all tests_require for bootstrap test (#298)

.travis.yml

@@ -10,7 +10,7 @@ install:
   # install_requires
   - pip install -U distlib EmPy pytest-rerunfailures pytest pytest-cov pytest-repeat pytest-runner
   # additional tests_require
-  - if [ "$TEST_SUITE" = "pytest" ]; then pip install -U flake8-blind-except flake8-builtins flake8-class-newline flake8-comprehensions flake8-deprecated flake8-docstrings flake8-quotes pep8-naming pylint scspell3k; fi
+  - pip install -U flake8-blind-except flake8-builtins flake8-class-newline flake8-comprehensions flake8-deprecated flake8-docstrings flake8-quotes pep8-naming pylint scspell3k
   # for uploading the coverage information to codecov
   - if [ "$TEST_SUITE" = "pytest" ]; then pip install codecov; fi
 script: