Module#const_get

Specs fixed:

Module#const_get
- calls #const_missing on the receiver if unable to locate the constant
More passing specs

Specs untagged:

Module#const_missing
- is called when an undefined constant is referenced via #const_get
Module#const_missing

Specs fixed:

Module#const_missing
- raises NameError and includes the name of the value that wasn't found
Check if we are Object
Merge pull request #715 from krekoten/module_const_get

Module#const_get