test: move unit/ to test/

This virtually reverts commit 436218d
('move unit tests to unit'), that was made in the scope of #106.

Despite the fact that testing of the connector uses `unittest`
framework, it is functional (and integration) testing by its nature:
most of the test cases verify that public API of the connector properly
works with tarantool.

In seems meaningful to locate such kind of test cases in the `test/`
directory, not `unit/`, disregarding of used framework.

Follows up #106.

Author: Totktonada

README.rst

@@ -97,7 +97,7 @@ On Linux:
 On Windows:
 
 * Setup a Linux machine with installed tarantool (called ``remote`` later).
-* (on ``remote``) Copy ``unit/suites/lib/tarantool_python_ci.lua`` to
+* (on ``remote``) Copy ``test/suites/lib/tarantool_python_ci.lua`` to
   ``/etc/tarantool/instances.available``.
 * (on ``remote``) Run ``tarantoolctl start tarantool_python_ci``.
 * Set the following environment variables:

setup.py

@@ -39,7 +39,7 @@
 # Test runner
 # python setup.py test
 try:
-    from unit.setup_command import test
+    from test.setup_command import test
     cmdclass["test"] = test
 except ImportError:
     pass

unit/__init__.py renamed to test/__init__.py

@@ -10,7 +10,7 @@
 
 class test(setuptools.Command):
     user_options = []
-    description = 'Run unit tests'
+    description = 'Run tests'
 
     def initialize_options(self):
         pass
@@ -23,7 +23,7 @@ def run(self):
         Find all tests in test/tarantool/ and run them
         '''
 
-        tests = unittest.defaultTestLoader.discover('unit', pattern='suites')
+        tests = unittest.defaultTestLoader.discover('test', pattern='suites')
         test_runner = unittest.TextTestRunner(verbosity=2)
         result = test_runner.run(tests)
         if not result.wasSuccessful():