Refactoring of the ControlParameter smell detector

Refactoring of the ControlParamater smell class to fix issues related to
smells and other non-smell issues.

For issue #231.
Small refactorings to remove some code smells.

For issue #231.
Merge pull request #251 from gilles-leblanc/reek_smell_free_2

Small refactorings to remove some code smells.
Improve statement counting

- Make the counting of statements in iterators consistent: We now always count
  both the main iterator statement and each of the statements inside the block
- Correctly count statements in the else clause of a case statement. This was
  both not specced and broken
- Always consider lone nils to be statements
- Move generation of module name inside ModuleContext, making its interface more
  consistent with the other CodeContext classes
- Make specs more complete and clean
- Simplify implementation of CodeParser
- Update cukes to match improved statement counting
Merge pull request #253 from troessner/issue-improve-too-many-statements

Improve statement counting
Merge pull request #249 from gilles-leblanc/control_parameter_smell_free

Refactoring of the ControlParameter smell detector