Implement Cobra CLI tooling, Viper config tooling (#336)

* start pulling out + replacing urfave and config

* replace many many instances of config

* move more stuff => viper

* properly remove urfave

* move some flags to root command

* add testrig commands to root

* alias config file keys

* start adding cli parsing tests

* reorder viper init

* remove config path alias

* fmt

* change config file keys to non-nested

* we're more or less in business now

* tidy up the common func

* go fmt

* get tests passing again

* add note about the cliparsing tests

* reorganize

* update docs with changes

* structure cmd dir better

* rename + move some files around

* fix dangling comma

vendor/github.com/spf13/jwalterweatherman/log_counter.go

@@ -0,0 +1,46 @@
+// Copyright © 2016 Steve Francia <spf@spf13.com>.
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package jwalterweatherman
+
+import (
+	"io"
+	"sync/atomic"
+)
+
+// Counter is an io.Writer that increments a counter on Write.
+type Counter struct {
+	count uint64
+}
+
+func (c *Counter) incr() {
+	atomic.AddUint64(&c.count, 1)
+}
+
+// Reset resets the counter.
+func (c *Counter) Reset() {
+	atomic.StoreUint64(&c.count, 0)
+}
+
+// Count returns the current count.
+func (c *Counter) Count() uint64 {
+	return atomic.LoadUint64(&c.count)
+}
+
+func (c *Counter) Write(p []byte) (n int, err error) {
+	c.incr()
+	return len(p), nil
+}
+
+// LogCounter creates a LogListener that counts log statements >= the given threshold.
+func LogCounter(counter *Counter, t1 Threshold) LogListener {
+	return func(t2 Threshold) io.Writer {
+		if t2 < t1 {
+			// Not interested in this threshold.
+			return nil
+		}
+		return counter
+	}
+}