[tests] Fix imports for Python3 compatibility

tests/test_engine.py

@@ -8,7 +8,7 @@ from bumblebee.engine import Engine
 from bumblebee.config import Config
 import bumblebee.input
 
-from mocks import MockOutput, MockInput
+from tests.mocks import MockOutput, MockInput
 
 class TestEngine(unittest.TestCase):
     def setUp(self):

tests/test_i3barinput.py

@@ -4,7 +4,7 @@ import json
 import mock
 import unittest
 
-import mocks
+import tests.mocks as mocks
 
 from bumblebee.input import I3BarInput, LEFT_MOUSE, RIGHT_MOUSE
 

tests/test_i3baroutput.py

@@ -9,7 +9,7 @@ try:
 except ImportError:
     from io import StringIO
 
-import mocks
+import tests.mocks as mocks
 
 from bumblebee.output import I3BarOutput
 

tests/test_module.py

@@ -4,7 +4,7 @@ import unittest
 
 from bumblebee.engine import Module
 from bumblebee.config import Config
-from mocks import MockWidget
+from tests.mocks import MockWidget
 
 class TestModule(unittest.TestCase):
     def setUp(self):

tests/test_theme.py

@@ -4,7 +4,7 @@ import mock
 import unittest
 from bumblebee.theme import Theme
 from bumblebee.error import ThemeLoadError
-from mocks import MockWidget
+from tests.mocks import MockWidget
 
 class TestTheme(unittest.TestCase):
     def setUp(self):

tests/test_util.py

@@ -3,7 +3,7 @@
 import mock
 import unittest
 
-import mocks
+import tests.mocks as mocks
 
 from bumblebee.util import *