Missing int tuple index should raise KeyError, not TypeError
#### Code Sample, a copy-pastable example if possible

```python
import pandas
pandas.DataFrame({"a": [0], "b": [0], "c": [0]}).set_index(["a", "b"]).loc[(0, 1)]
```

#### Problem description
It should raise `KeyError` because `(0, 1)` doesn’t exist, like Pandas used to.  I had some old code that relied on this behavior.

Currently it raises a `TypeError`, which is confusing because it’s telling me that I can’t index using `(int, int)`, even though it works just fine if I called `.loc[(0, 0)]`.

#### Actual output

    TypeError: cannot do label indexing on <class 'pandas.core.indexes.base.Index'> with these indexers [1] of <class 'int'>

#### Expected Output

    KeyError: 'the label [(0, 1)] is not in the [index]'

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

<details>

```
INSTALLED VERSIONS
------------------
commit: None
python: 3.6.4.final.0
python-bits: 64
OS: Linux
OS-release: 4.14.8-1-ARCH
machine: x86_64
processor: 
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

pandas: 0.23.0.dev0+27.gcfa5ea696
pytest: None
pip: 9.0.1
setuptools: 38.2.5
Cython: 0.27.3
numpy: 1.13.3
scipy: 1.0.0
pyarrow: None
xarray: None
IPython: 6.2.1
sphinx: 1.6.5
patsy: None
dateutil: 2.6.1
pytz: 2017.3
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: 2.1.1
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: None
sqlalchemy: 1.1.15
pymysql: None
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None
```

</details>
