Adjust Rakefile
Add basis specs
Little refactoring for core.rb
Merge pull request #10 from gogotanaka/add_specs_and_little_refactoring

Add specs and trivial refactoring
Init EgisonArray to identify LazyArray with Array
Add specs for constructor
Merge pull request #12 from gogotanaka/identify_lazy_array_with_array

Identify LazyArray with Array
Merge pull request #13 from gogotanaka/add_specs_for_constructor

Add specs for constructor