Add SLF4j and Logback dependencies.
Initial logging configuration: basic console logging, limit entries from
runtime and third party tools.

Disable debug in Keen.
Disabled logging in KeenClient, added first logging messages, renamed
LogManager.
Add basic logging to all of the new JSoup parsing classes. Will need to
be more thorough in the future, but this is a start.
Replaced System.out and System.err messages with SLF4J logging.

Cleaned up some resource leak issues. Minor cleanup.
Minor cleanup to Main method.
Merge pull request #16 from CourseScheduler/feature-logging

Add SLF4J based logging.