Switch to using a named logger so callers can configure log levels.

[psobot]

Closes #51. This is kind of hacky, but should work and should allow callers to configure pysox logging via logging.getLogger('sox') on the global logging object.

[coveralls]

Coverage increased (+0.004%) to 98.751% when pulling 3047f19 on psobot:psobot/named-logger into 49dfb16 on rabitt:master.

[coveralls]

Coverage increased (+0.004%) to 98.751% when pulling 74a3b51 on psobot:psobot/named-logger into 49dfb16 on rabitt:master.

[coveralls]

Coverage increased (+0.004%) to 98.751% when pulling 74a3b51 on psobot:psobot/named-logger into 49dfb16 on rabitt:master.

[coveralls]

Coverage increased (+0.004%) to 98.751% when pulling 74a3b51 on psobot:psobot/named-logger into 49dfb16 on rabitt:master.

[coveralls]

Coverage increased (+0.004%) to 98.751% when pulling 726b5c6 on psobot:psobot/named-logger into 49dfb16 on rabitt:master.

[rabitt]

👍 Thanks @psobot !