Add new ScopeDescriptor object
Return ScopeDescriptor objects
Update descriptor docs
ScopeDescriptor::create -> fromObject
Fix specs
Return scopes arrays from deprecated methods

backward compatibility
scopeDescriptor -> scopes

Now that we have a real ScopeDescriptor object, 
these should change back!
Oops, don’t call the method twice
Last of scopeDescriptor -> scopes from tokens
Fix comments n junk
Merge pull request #3910 from atom/bo-descriptor-object

Add a ScopeDescriptor object