Show cookbook version number only once in syntax checker error message

Before: Ridley::Errors::CookbookSyntaxError Invalid template files in
cookbook: ridley_test-0.1.0 (0.1.0).
After: Ridley::Errors::CookbookSyntaxError Invalid template files in
cookbook: ridley_test (0.1.0).
Refactor untested_*_files for readability
Show syntax check output on error

Before: Ridley::Errors::CookbookSyntaxError Invalid template files in
cookbook: ridley_test (0.1.0).
After: Erb template templates/default/defect.erb has a syntax error:
-:1: syntax error, unexpected '>'
Ridley::Errors::CookbookSyntaxError Invalid template files in cookbook:
ridley_test (0.1.0).
Merge pull request #82 from promisedlandt/master

Improved syntax checker error output