option: add a Text-based presenter

Signed-off-by: Alfredo Deza <adeza@anchore.com>

imgbom/presenter/option.go

@@ -5,15 +5,18 @@ import "strings"
 const (
 	UnknownPresenter Option = iota
 	JSONPresenter
+	TextPresenter
 )
 
 var optionStr = []string{
 	"UnknownPresenter",
 	"json",
+	"text",
 }
 
 var Options = []Option{
 	JSONPresenter,
+	TextPresenter,
 }
 
 type Option int
@@ -22,6 +25,8 @@ func ParseOption(userStr string) Option {
 	switch strings.ToLower(userStr) {
 	case strings.ToLower(JSONPresenter.String()):
 		return JSONPresenter
+	case strings.ToLower(TextPresenter.String()):
+		return TextPresenter
 	default:
 		return UnknownPresenter
 	}

imgbom/presenter/text/test-fixtures/image-simple/Dockerfile

@@ -0,0 +1,4 @@
+# Note: changes to this file will result in updating several test values. Consider making a new image fixture instead of editing this one.
+FROM scratch
+ADD file-1.txt /somefile-1.txt
+ADD file-2.txt /somefile-2.txt

imgbom/presenter/text/test-fixtures/image-simple/file-1.txt

@@ -0,0 +1 @@
+this file has contents

imgbom/presenter/text/test-fixtures/image-simple/file-2.txt

@@ -0,0 +1 @@
+file-2 contents!

imgbom/presenter/text/test-fixtures/snapshot/TestTextPresenter.golden

@@ -0,0 +1,28 @@
+[Image]
+ Layer:		 0
+ Digest:	 sha256:056c0789fa9ad629ceae6d09713fb035f84115af3c4a88a43aa60f13bc683053
+ Size:		 22
+ MediaType:	 application/vnd.docker.image.rootfs.diff.tar.gzip
+
+ Layer:		 1
+ Digest:	 sha256:b461c48116592c570a66fed71d5b09662a8172e168b7938cf317af47872cdc9b
+ Size:		 16
+ MediaType:	 application/vnd.docker.image.rootfs.diff.tar.gzip
+
+ Layer:		 2
+ Digest:	 sha256:00b80053e05c01da485015610d288ce3185fac00d251e2ada02b45a7a7c5f589
+ Size:		 27
+ MediaType:	 application/vnd.docker.image.rootfs.diff.tar.gzip
+
+[package-1]
+ Version:	 1.0.1
+ Type:		 deb
+ Metadata:	 <nil>
+ Found by:	 dpkg
+
+[package-2]
+ Version:	 2.0.1
+ Type:		 deb
+ Metadata:	 {package-2 1.0.2}
+ Found by:	 dpkg
+