BasicObject includes itself as a constant

Specs fixed:

BasicObject
- includes itself in its list of constants
Fixed constant resolving

Specs fixed:

BasicObject
- raises NameError when referencing built-in constants
Fixed defined? for constants

Specs fixed:

BasicObject
- does not define built-in constants (according to defined?)
Break if not Class
Changes per request
should be space, not self
Merge branch 'master' into constant_lookup

Conflicts:
	spec/tags/core/basicobject/basicobject_tags.txt
Merge pull request #705 from krekoten/constant_lookup

Constant lookup