UPDATE: improved comments
UPDATE: remove unnecessary URL filtering on playback

* Removed URL check for audio stream from "pandora.com" or "p-cdn.com"
  - URL check doesn't seem to serve a purpose (? checking for ads?)
  - URL check added maintenance headache if/when Pandora changes stream sources (eg, different CDN)
* Improved comments
UPDATE: refactor & improve logging code

* Logging code condensed into a class with better module usage semantics
* Override python logging for library submodules to capture, control, and reframe log output
UPDATE: remove redundant code

* Removed unneeded extra sys.path.append()'s from submodules
* Removed unneded access to addon properties
UPDATE: improved firstrun logic

* Allow for user setup of required username/password prior to actual first run
UPDATE: increase level of log instrumentation

* Added more log instrumentation to assist in diagnosing odd crash reports