Add support for time() and timeEnd() like in `console`

The node console logger has a very useful timing function that allows the developer to easily generate operation timing logs to allow her to collect statistics on the run time performance of the application.

By replacing the console logger with log4js, this capability is lost. This pull request adds similar functionality with optional support for selecting the logging level of the time report.

Implementation is modeled after the log4javascript implementation, though it is new and (somewhat) different.