Add possibility to run bok_choy tests in local env.

This PR will allow to run bok_choy test in native dev env w/o vagrant and virtualbox

1. Run mysqld, mongod and memcached
2. Create, if they are not exist, two private.py files in cms/envs and lms/envs and add following code to them:


In lms/envs/private.py add:
```python
"""
My custom settings.
"""
import os
from logsettings import get_logger_config


from .common import REPO_ROOT
from .aws import ENV_TOKENS


if os.environ['SERVICE_VARIANT'] == 'bok_choy':
    LOGGING = get_logger_config(REPO_ROOT + '/log',
                            logging_env=ENV_TOKENS['LOGGING_ENV'],
                            syslog_addr=(ENV_TOKENS['SYSLOG_SERVER'], 514),
                            local_loglevel=ENV_TOKENS.get('LOCAL_LOGLEVEL', 'INFO'),
                            debug=False,
                            dev_env=True,
                            service_variant=os.environ['SERVICE_VARIANT'])
```

In cms/envs/private.py add:
```python
"""
My custom settings.
"""
import os
from logsettings import get_logger_config


from .common import REPO_ROOT
from .aws import ENV_TOKENS


if os.environ['SERVICE_VARIANT'] == 'bok_choy':
    LOGGING = get_logger_config(REPO_ROOT + '/log',
                            logging_env=ENV_TOKENS['LOGGING_ENV'],
                            syslog_addr=(ENV_TOKENS['SYSLOG_SERVER'], 514),
                            debug=False,
                            dev_env=True,
                            service_variant=os.environ['SERVICE_VARIANT'])
```

then you will be able to run bok_choy tests.

@jzoldak please review