BUG: HDFStore fixes

- shape attribute on GenericStorer returns tuple correctly now (not string)
- data_orientation was potentitally returning non-ints in a tuple (fixed downstream), fixes GH #2671, though fixed downstream anyhow
- fix for contains with a non-natural name (GH #2694 )
- added ability to read generic PyTables flavor tables
- added PerformanceWarning to trigger on putting of non-endemic types (only on Storers)
- correctly store float32 dtypes (when not-mixed with float64, otherwise converted)
- can close  GH  #1985 as well