Switch from nose to pytest + coverage.

.gitignore

@@ -4,3 +4,4 @@ venv/*
 *.pyc
 .eggs
 docs/_build/*
+.coverage

.travis.yml

@@ -1,5 +1,5 @@
 language: python
 install:
-- pip install nose tornado click python-magic
+- pip install pytest pytest-cov tornado click python-magic
 script:
 - python setup.py test

setup.cfg

@@ -0,0 +1,5 @@
+[aliases]
+test=pytest
+
+[tool:pytest]
+addopts = --cov=gb

setup.py

@@ -9,9 +9,9 @@ setup(
     author="supakeen",
     author_email="cmdr@supakeen.com",
     packages=[],
+    setup_requires=["pytest-runner", "pytest-cov"],
     install_requires=["tornado", "click", "python-magic"],
     entry_points={"console_scripts": ["gb=gb.command:main"]},
-    tests_require=["nose", "aiounittest"],
+    tests_require=["pytest", "pytest-cov"],
     extras_require={"dev": ["pre-commit", "flake8", "black", "nose"]},
-    test_suite="nose.collector",
 )