#65 per-request allocation reduction destroys this module

[mgabeler-lee-6rs]

PR #65, in an attempt to reduce allocations, actually wrecks this module and makes the output insane in some cases, and introduces a humongous memory leak.

The problem is that the returned gin.HandlerFunc closes over l the logger variable. Therefore, requests stomp over each other, modifying the same context buffers inside the logger, as a nice data race for good measure, and overall resulting in the data from every request ever issued being captured, leaking memory and making a mess of the output.

logger/logger.go

Lines 107 to 113 in 7cff53e

	l = l.With().
	Int("status", c.Writer.Status()).
	Str("method", c.Request.Method).
	Str("path", path).
	Str("ip", c.ClientIP()).
	Dur("latency", latency).
	Str("user_agent", c.Request.UserAgent()).Logger()

The tests didn't notice this because they all use a ConsoleWriter, which obscures this duplication.

I think the fix is simple: create an event at that line instead of mutating the logger. Submitted #69 with a fix for this, and a test which demonstrates the issue.