Improve overall documentation (#148)

* improve overall documentation

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

* fix tests to use scope.Resolver over scope

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

syft/presenter/json/presenter_test.go

@@ -39,7 +39,7 @@ func TestJsonDirsPresenter(t *testing.T) {
 		},
 	})
 
-	s, err := scope.NewScopeFromDir("/some/path", scope.AllLayersScope)
+	s, err := scope.NewScopeFromDir("/some/path")
 	if err != nil {
 		t.Fatal(err)
 	}

syft/presenter/presenter.go

@@ -1,3 +1,7 @@
+/*
+Defines a Presenter interface for displaying catalog results to an io.Writer as well as a helper utility to obtain
+a specific Presenter implementation given user configuration.
+*/
 package presenter
 
 import (
@@ -10,6 +14,8 @@ import (
 	"github.com/anchore/syft/syft/scope"
 )
 
+// Presenter defines the expected behavior for an object responsible for displaying arbitrary input and processed data
+// to a given io.Writer.
 type Presenter interface {
 	Present(io.Writer) error
 }

syft/presenter/text/presenter_test.go

@@ -31,7 +31,7 @@ func TestTextDirPresenter(t *testing.T) {
 		Type:    pkg.DebPkg,
 	})
 
-	s, err := scope.NewScopeFromDir("/some/path", scope.AllLayersScope)
+	s, err := scope.NewScopeFromDir("/some/path")
 	if err != nil {
 		t.Fatalf("unable to create scope: %+v", err)
 	}