correct race condition in iterator_refresh code that can cause segfault on stale m_Options pointer
Add test cases to iterators test module

Refactor the iterators test module to use an eunit test suite to
manage scaffolding. Add three new test cases: one for testing SEEK and
NEXT actions together and two for testing PREFETCH actions.
implement prefetch_stop to allow reuse of iterator that is performing prefetch operations.
remove all ReadOption pointers from iterator objects.  use as embedded struct
correct typo
Update to seek_and_prefetch iterator test case
address errors found by Kelly via test/iterators.erl ... and add test there for another case that failed
Merge pull request #93 from basho/mv-tuning4

Mv tuning4