fixed minor typos in my_enumerable tests
Merge pull request #9 from svetliomihailov/fix_enumerable_tests

fixed minor typos in my_enumerable tests
Add Enumerator challenges to the mix
Add #group_by to the mix
Add even more methods
Strict mode
Fix a typo
Merge branch 'master' of https://github.com/HackBulgaria/Core-Ruby-1