Using the python power operator on numerical Index objects yields unexpected results
#### Code Sample, a copy-pastable example if possible

```python
index = pd.Float64Index(range(1, 11))

expected_pow_values = 2.0**index.values
actual_pow_values = 2.0**index
similar_pow_values = 2.0**np.arange(len(index))

expected_mul_values = 2.0*index.values
actual_mul_values = 2.0*index

other_way_around = index**2.0
same_as = index.values**2.0

```
#### Problem description

Using the pow '**' operator on an index object results in a behaviour different than when using the '*' operator. The pow result implies that the values being used are not index.values, which one would expect given the behaviour of other operators (*, -, +, / ...).
This problem only arises when the index object is the second argument.

#### Expected Output
expected output would be the result of 2.0**index.values

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

<details>

commit: None
python: 2.7.13.final.0
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 42 Stepping 7, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None
LOCALE: None.None

pandas: 0.19.1
nose: None
pip: 9.0.1
setuptools: 32.2.0
Cython: None
numpy: 1.12.0rc1
scipy: 0.18.1
statsmodels: 0.8.0rc1
xarray: None
IPython: 5.1.0
sphinx: 1.4.8
patsy: 0.4.1
dateutil: 2.6.0
pytz: 2016.10
blosc: None
bottleneck: None
tables: None
numexpr: None
matplotlib: 1.5.3
openpyxl: 2.4.1
xlrd: 1.0.0
xlwt: 1.1.2
xlsxwriter: None
lxml: 3.7.0
bs4: None
html5lib: 0.9999999
httplib2: None
apiclient: None
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: 2.8
boto: None

</details>
