Add BoolFlag for rawdatastore.

service/rawdatastore/properties.go

Index: service/rawdatastore/properties.go
diff --git a/service/rawdatastore/properties.go b/service/rawdatastore/properties.go
index f1e0341b59ce539577bd59ae536eeec678bb991b..2092a5c73057e39b514eeed871d18402f43c31ea 100644
--- a/service/rawdatastore/properties.go
+++ b/service/rawdatastore/properties.go
@@ -347,6 +347,20 @@ type PropertyLoadSaver interface {
 	//   val, err := helper.GetPLS(&MyStruct{10}).GetMeta("id")
 	//   // val == 10
 	//   // err == nil
+	//
+	// Struct fields of type BoolFlag (which is an Auto/False/True) allow you to
+	// specify a value of 'true' or 'false' for the default value of the struct
+	// tag, and GetMeta will return the combined value as a regular boolean true
+	// or false value. If a field is BoolFlag, and no <value> is specified,
+	// GetMeta will return false. A simple boolean field creates ambiguity with
+	// a default <value>.
+	//
+	// Example:
+	//   type MyStruct struct {
+	//     TFlag BoolFlag `gae:"$flag1,true"`  // defaults to true
+	//     FFlag BoolFlag `gae:"$flag2,false"` // defaults to false
+	//     Flag  BoolFlag `gae:"$flag3"`       // defaults to false
+	//   }
 	GetMeta(key string) (interface{}, error)
 
 	// SetMeta allows you to set the current value of the meta-keyed field.