Add route53 plugin (#1390)

* Update vendor

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Add route53 plugin

This fix adds route53 plugin so that it is possible to
query route53 record through CoreDNS.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

vendor/github.com/jmespath/go-jmespath/api.go

@@ -0,0 +1,49 @@
+package jmespath
+
+import "strconv"
+
+// JmesPath is the epresentation of a compiled JMES path query. A JmesPath is
+// safe for concurrent use by multiple goroutines.
+type JMESPath struct {
+	ast  ASTNode
+	intr *treeInterpreter
+}
+
+// Compile parses a JMESPath expression and returns, if successful, a JMESPath
+// object that can be used to match against data.
+func Compile(expression string) (*JMESPath, error) {
+	parser := NewParser()
+	ast, err := parser.Parse(expression)
+	if err != nil {
+		return nil, err
+	}
+	jmespath := &JMESPath{ast: ast, intr: newInterpreter()}
+	return jmespath, nil
+}
+
+// MustCompile is like Compile but panics if the expression cannot be parsed.
+// It simplifies safe initialization of global variables holding compiled
+// JMESPaths.
+func MustCompile(expression string) *JMESPath {
+	jmespath, err := Compile(expression)
+	if err != nil {
+		panic(`jmespath: Compile(` + strconv.Quote(expression) + `): ` + err.Error())
+	}
+	return jmespath
+}
+
+// Search evaluates a JMESPath expression against input data and returns the result.
+func (jp *JMESPath) Search(data interface{}) (interface{}, error) {
+	return jp.intr.Execute(jp.ast, data)
+}
+
+// Search evaluates a JMESPath expression against input data and returns the result.
+func Search(expression string, data interface{}) (interface{}, error) {
+	intr := newInterpreter()
+	parser := NewParser()
+	ast, err := parser.Parse(expression)
+	if err != nil {
+		return nil, err
+	}
+	return intr.Execute(ast, data)
+}