Limit log disk space with log rolling

To balance the need for logs while considering disk usage, each .NET agent will limit disk usage to 250MB using log rolling. The agent will first log to the file newrelic_agent_UNIQUENAME.log and create the file if it doesn't exist. Once that file reaches 50MB in size, the agent will:

1. Create a new log file.
2. Roll each existing log file to a new, sequentially numbered name (up to four archived files).
3. Delete the fourth archive.

To roll the log files, the old newrelic_agent_UNIQUENAME.log becomes the new newrelic_agent_UNIQUENAME.log(1). Then, the old newrelic_agent_UNIQUENAME.log(1) becomes the new newrelic_agent_UNIQUENAME.log(2), and so on. The old newrelic_agent_UNIQUENAME.log(4) is deleted.