Dict/dict keys in DataFrame.__getitem__
#### Code Sample, a copy-pastable example if possible

```python
In [2]: pd.Series(index=range(10))[{1:2,3:4}]
Out[2]: 
1   NaN
3   NaN
dtype: float64

In [3]: pd.Series(index=range(10))[{1:2,3:4}.keys()]
Out[3]: 
1   NaN
3   NaN
dtype: float64

In [4]: pd.DataFrame(index=range(10), columns=range(10))[{1:2,3:4}]
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-5b29d5d42cf2> in <module>()
----> 1 pd.DataFrame(index=range(10), columns=range(10))[{1:2,3:4}]

~/nobackup/repo/pandas/pandas/core/frame.py in __getitem__(self, key)
   2683             return self._getitem_multilevel(key)
   2684         else:
-> 2685             return self._getitem_column(key)
   2686 
   2687     def _getitem_column(self, key):

~/nobackup/repo/pandas/pandas/core/frame.py in _getitem_column(self, key)
   2690         # get column
   2691         if self.columns.is_unique:
-> 2692             return self._get_item_cache(key)
   2693 
   2694         # duplicate columns & possible reduce dimensionality

~/nobackup/repo/pandas/pandas/core/generic.py in _get_item_cache(self, item)
   2482         """Return the cached item, item represents a label indexer."""
   2483         cache = self._item_cache
-> 2484         res = cache.get(item)
   2485         if res is None:
   2486             values = self._data.get(item)

TypeError: unhashable type: 'dict'

In [5]: pd.DataFrame(index=range(10), columns=range(10))[{1:2,3:4}.keys()]
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-5-030f516d9637> in <module>()
----> 1 pd.DataFrame(index=range(10), columns=range(10))[{1:2,3:4}.keys()]

~/nobackup/repo/pandas/pandas/core/frame.py in __getitem__(self, key)
   2683             return self._getitem_multilevel(key)
   2684         else:
-> 2685             return self._getitem_column(key)
   2686 
   2687     def _getitem_column(self, key):

~/nobackup/repo/pandas/pandas/core/frame.py in _getitem_column(self, key)
   2690         # get column
   2691         if self.columns.is_unique:
-> 2692             return self._get_item_cache(key)
   2693 
   2694         # duplicate columns & possible reduce dimensionality

~/nobackup/repo/pandas/pandas/core/generic.py in _get_item_cache(self, item)
   2482         """Return the cached item, item represents a label indexer."""
   2483         cache = self._item_cache
-> 2484         res = cache.get(item)
   2485         if res is None:
   2486             values = self._data.get(item)

TypeError: unhashable type: 'dict_keys'
```

#### Problem description

I know that ``DataFrame.__getitem__`` is a mess ( #9595 ), but I don't see why dicts and dict keys shouldn't be just considered list-likes as it happens with ``Series``.

#### Expected Output

```python
In [6]: pd.DataFrame(index=range(10), columns=range(10))[list({1:2,3:4})]
Out[6]: 
     1    3
0  NaN  NaN
1  NaN  NaN
2  NaN  NaN
3  NaN  NaN
4  NaN  NaN
5  NaN  NaN
6  NaN  NaN
7  NaN  NaN
8  NaN  NaN
9  NaN  NaN
```

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

<details>

INSTALLED VERSIONS
------------------
commit: None
python: 3.5.3.final.0
python-bits: 64
OS: Linux
OS-release: 4.9.0-6-amd64
machine: x86_64
processor: 
byteorder: little
LC_ALL: None
LANG: it_IT.UTF-8
LOCALE: it_IT.UTF-8

pandas: 0.24.0.dev0+25.gcd0447102
pytest: 3.5.0
pip: 9.0.1
setuptools: 39.2.0
Cython: 0.25.2
numpy: 1.14.3
scipy: 0.19.0
pyarrow: None
xarray: None
IPython: 6.2.1
sphinx: 1.5.6
patsy: 0.5.0
dateutil: 2.7.3
pytz: 2018.4
blosc: None
bottleneck: 1.2.0dev
tables: 3.3.0
numexpr: 2.6.1
feather: 0.3.1
matplotlib: 2.2.2.post1153+gff6786446
openpyxl: 2.3.0
xlrd: 1.0.0
xlwt: 1.3.0
xlsxwriter: 0.9.6
lxml: 4.1.1
bs4: 4.5.3
html5lib: 0.999999999
sqlalchemy: 1.0.15
pymysql: None
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: 0.2.1


</details>
