Improve logging capabilities

[Nightfirecat]

It would be nice to have some level of application logging for maintenance as needed. (INFO/WARN/DEBUG)

EDIT:

In full, I'd like to see the following features implemented for this application:

• [x] Log levels (DEBUG/ERROR/WARN/INFO). Maybe implement others? Ref: https://en.wikipedia.org/wiki/Log4j#Log4j_log_levels
• [x] Logger should be its own class rather than a global function
• [x] Output lines must indicate originating file
• [x] (nice-to-have) Output logs should ideally indicate originating line in file

[Nightfirecat]

For logging the originating file / method / line, http://stackoverflow.com/a/1252559/540162

[Nightfirecat]

Also, for reference on how other languages implement loggers: https://docs.oracle.com/javase/8/docs/api/java/util/logging/Logger.html

[Nightfirecat]

Examples of log statements: (for personal reference)

09.03.2017 12:34:56.987 *INFO* [pool-1-thread-2] com.org.product.Class message

[Thu Mar 09 12:34:56 2017] [info] message