format ignored in HDFStore.open
```
new_store = pd.HDFStore('data/test.h5', format='table')
new_store['df'] = pd.DataFrame(np.random.rand(5,1))
new_store.put('df2', pd.DataFrame(np.random.rand(5,1)), format='table')
print('df stored as table: %s' % new_store.get_storer('df').is_table)
print('df2 stored as table: %s' % new_store.get_storer('df2').is_table)
```

df stored as table: False
df2 stored as table: True
## INSTALLED VERSIONS

commit: None
python: 2.7.11.final.0
python-bits: 64
OS: Linux
OS-release: 3.16.0-30-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.18.0
