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/viper/flags.go

@@ -0,0 +1,57 @@
+package viper
+
+import "github.com/spf13/pflag"
+
+// FlagValueSet is an interface that users can implement
+// to bind a set of flags to viper.
+type FlagValueSet interface {
+	VisitAll(fn func(FlagValue))
+}
+
+// FlagValue is an interface that users can implement
+// to bind different flags to viper.
+type FlagValue interface {
+	HasChanged() bool
+	Name() string
+	ValueString() string
+	ValueType() string
+}
+
+// pflagValueSet is a wrapper around *pflag.ValueSet
+// that implements FlagValueSet.
+type pflagValueSet struct {
+	flags *pflag.FlagSet
+}
+
+// VisitAll iterates over all *pflag.Flag inside the *pflag.FlagSet.
+func (p pflagValueSet) VisitAll(fn func(flag FlagValue)) {
+	p.flags.VisitAll(func(flag *pflag.Flag) {
+		fn(pflagValue{flag})
+	})
+}
+
+// pflagValue is a wrapper aroung *pflag.flag
+// that implements FlagValue
+type pflagValue struct {
+	flag *pflag.Flag
+}
+
+// HasChanged returns whether the flag has changes or not.
+func (p pflagValue) HasChanged() bool {
+	return p.flag.Changed
+}
+
+// Name returns the name of the flag.
+func (p pflagValue) Name() string {
+	return p.flag.Name
+}
+
+// ValueString returns the value of the flag as a string.
+func (p pflagValue) ValueString() string {
+	return p.flag.Value.String()
+}
+
+// ValueType returns the type of the flag as a string.
+func (p pflagValue) ValueType() string {
+	return p.flag.Value.Type()
+}