BUG: HDFStore fixed format not decoding meta-data in PY3
#### Code Sample, a copy-pastable example if possible
In Python 2:
```python

df = pd.DataFrame([[1, 2], [3, 4]])
df.index.name = "date"
df.to_hdf('/tmp/test.hdf', 'test')
```
In Python 3:
```python

In [2]: pd.read_hdf('/tmp/test.hdf', 'test')
Out[2]: 
         0  1
b'date'      
0        1  2
1        3  4
```

#### Problem description

``b'date'`` should actually be just ``date``

#### Expected Output

``` python

Out[2]: 
         0  1
date      
0        1  2
1        3  4
```

#### Output of ``pd.show_versions()``

<details>

INSTALLED VERSIONS
------------------
commit: None
python: 3.5.3.final.0
python-bits: 64
OS: Linux
OS-release: 4.7.0-1-amd64
machine: x86_64
processor: 
byteorder: little
LC_ALL: None
LANG: it_IT.utf8
LOCALE: it_IT.UTF-8

pandas: 0.19.0+603.g2cad4dd0b
pytest: 3.0.6
pip: 9.0.1
setuptools: 33.1.1
Cython: 0.25.2
numpy: 1.12.0
scipy: 0.18.1
xarray: 0.9.1
IPython: 5.1.0.dev
sphinx: 1.4.9
patsy: 0.3.0-dev
dateutil: 2.5.3
pytz: 2016.7
blosc: None
bottleneck: 1.2.0
tables: 3.3.0
numexpr: 2.6.1
feather: 0.3.1
matplotlib: 2.0.0
openpyxl: 2.3.0
xlrd: 1.0.0
xlwt: 1.1.2
xlsxwriter: 0.9.6
lxml: 3.7.1
bs4: 4.5.3
html5lib: 0.999999999
sqlalchemy: 1.0.15
pymysql: None
psycopg2: None
jinja2: 2.8
s3fs: None
pandas_gbq: None
pandas_datareader: 0.2.1

</details>
