Update README.md
Update README.md
Update README.md
Fixed a line missing to set the default context
Merge pull request #20 from SugarRecord/defaultContextMissing

Fixed a line missing to set the default context
Update README.md
Merge branch 'develop' into newStackStructure

Conflicts:
	SugarRecord/NSManagedObjectContext/NSManagedObjectContext+Stack.swift