Update github flowconfigs to enable exact_empty_objects option

Summary:
The empty object literal `{}` now has the type `{}` - i.e. an exact empty object - rather than being unsealed.

Enable the option in the github flowconfigs

Changelog: [Internal]

Reviewed By: pieterv

Differential Revision: D37836634

fbshipit-source-id: 8ef0cfaf1d0420ae71723e04163f00c43c550e07

Author: gkz

.flowconfig

@@ -32,6 +32,7 @@ flow/
 emoji=true
 
 exact_by_default=true
+exact_empty_objects=true
 
 format.bracket_spacing=false
 

.flowconfig.android

@@ -32,6 +32,7 @@ flow/
 emoji=true
 
 exact_by_default=true
+exact_empty_objects=true
 
 format.bracket_spacing=false