Use setup.py to list requirements

requirements/ci.txt

@@ -1,9 +0,0 @@
--r common.txt
-
-pytest==2.8.2
-pytest-cov
-coverage
-codecov
-pep8
-pyflakes
-pylint

requirements/common.txt

@@ -1,9 +0,0 @@
-rethinkdb==2.2.0.post1
-pysha3==0.3
-pytz==2015.7
-cryptography==1.2.1
-statsd==3.2.1
-python-rapidjson==0.0.6
-logstats==0.2.1
-base58==0.2.2
-bitcoin==1.1.42

setup.py

@@ -6,6 +6,16 @@ For full docs visit https://bigchaindb.readthedocs.org
 """
 from setuptools import setup
 
+tests_require = [
+    'pytest',
+    'coverage',
+    'pep8',
+    'pyflakes',
+    'pylint',
+    'pytest',
+    'pytest-cov',
+]
+
 setup(
     name='BigchainDB',
     version='0.0.0',
@@ -45,5 +55,6 @@ setup(
         'bitcoin==1.1.42',
     ],
     setup_requires=['pytest-runner'],
-    tests_require=['pytest'],
+    tests_require=tests_require,
+    extras_require={'test': tests_require},
 )