Comprehensive logging [JIRA: CLIENTS-830]

[seancribbs]

Copied from https://github.com/seancribbs/ripple/issues/159 by @seancribbs:

All major operations, especially communications with the Riak host, should be logged with a configurable logger object.

# Should use Rails' logger in the railtie
Riak.logger = Rails.logger

# Allow setting a custom logger
Riak.logger = Logger.new(STDOUT)

It could default to a 'null' logger.

[boosty]

A custom logger object was introduced via #248.

[boosty]

@lukebakken It was not my intention to close this, since this issue sounds much bigger than just introducing the necessary logger object 😉 But you can decide... I guess it would still make sense to add more logging for the client operations.

[lukebakken]

Got it.