Hash_Index RSpec test file was created.
Spec tests updates in spec/hash_index.rb
Changes in implementation of lib/rod/index/hash_index.rb There was also spec/index/hash_index.rb file with tests added.
Changes in hash_index#open method - path argument not needed anymore, hash_index specs improved.
Little visual changes in spec/index/hash_index.rb, copy method test has been marked as 'to skip' because there are gaps in implementation, which does not allow for the proper conduct of this test.
Merge pull request #245 from zywszy/v0.7.x_index_spec

hash index spec