_compat.py import creates dependency on Mock library

[nichaladas]

The importing of the mock library in _compat.py has created a dependency on the mock library when trying to use rlog in a production environment.

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/VE/lib/python2.7/site-packages/logging_handler.py", line 20, in <module>
    from rlog import RedisHandler
  File "/VE/lib/python2.7/site-packages/rlog/__init__.py", line 2, in <module>
    from rlog.handlers import RedisHandler, RedisListHandler
  File "/VE/lib/python2.7/site-packages/rlog/handlers.py", line 5, in <module>
    from .formatters import JSONFormatter
  File "/VE/lib/python2.7/site-packages/rlog/formatters.py", line 6, in <module>
    from ._compat import json, text_type
  File "/VE/lib/python2.7/site-packages/rlog/_compat.py", line 18, in <module>
    from mock import patch, Mock
ImportError: No module named mock

[lobziik]

Now this import moved to separate file in tests module.

[lobziik]

Pypi version updated