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/hashicorp/hcl/lex.go

@@ -0,0 +1,38 @@
+package hcl
+
+import (
+	"unicode"
+	"unicode/utf8"
+)
+
+type lexModeValue byte
+
+const (
+	lexModeUnknown lexModeValue = iota
+	lexModeHcl
+	lexModeJson
+)
+
+// lexMode returns whether we're going to be parsing in JSON
+// mode or HCL mode.
+func lexMode(v []byte) lexModeValue {
+	var (
+		r      rune
+		w      int
+		offset int
+	)
+
+	for {
+		r, w = utf8.DecodeRune(v[offset:])
+		offset += w
+		if unicode.IsSpace(r) {
+			continue
+		}
+		if r == '{' {
+			return lexModeJson
+		}
+		break
+	}
+
+	return lexModeHcl
+}