FAIL: test_scatter_matrix_axis (pandas.tests.test_graphics_others.TestDataFramePlots) in 0.18.1 with py27
When run alone, `test_scatter_matrix_axis` passes. When run together with the rest of `TestDataFramePlots`, it fails.

I cannot test with py34 because matplotlib is not available on FreeBSD under py3k.
#### Code Sample, a copy-pastable example if possible

```
% nosetests-2.7 pandas.tests.test_graphics_others:TestDataFramePlots.test_scatter_matrix_axis
.
----------------------------------------------------------------------
Ran 1 test in 8.150s

OK
% nosetests-2.7 pandas.tests.test_graphics_others:TestDataFramePlots
..S/usr/local/lib/python2.7/site-packages/pandas/tools/plotting.py:3369: UserWarning: To output multiple subplots, the figure containing the passed axes is being cleared
  "the passed axes is being cleared", UserWarning)
/usr/local/lib/python2.7/site-packages/pandas/tools/plotting.py:3369: UserWarning: To output multiple subplots, the figure containing the passed axes is being cleared
  "the passed axes is being cleared", UserWarning)
/usr/local/lib/python2.7/site-packages/pandas/tools/plotting.py:3369: UserWarning: To output multiple subplots, the figure containing the passed axes is being cleared
  "the passed axes is being cleared", UserWarning)
/usr/local/lib/python2.7/site-packages/pandas/tools/plotting.py:3369: UserWarning: To output multiple subplots, the figure containing the passed axes is being cleared
  "the passed axes is being cleared", UserWarning)
/usr/local/lib/python2.7/site-packages/pandas/tools/plotting.py:3369: UserWarning: To output multiple subplots, the figure containing the passed axes is being cleared
  "the passed axes is being cleared", UserWarning)
/usr/local/lib/python2.7/site-packages/matplotlib/artist.py:221: MatplotlibDeprecationWarning: This has been deprecated in mpl 1.5, please use the
axes property.  A removal date has not been set.
  warnings.warn(_get_axes_msg, mplDeprecation, stacklevel=1)
/usr/local/lib/python2.7/site-packages/pandas/tools/plotting.py:3369: UserWarning: To output multiple subplots, the figure containing the passed axes is being cleared
  "the passed axes is being cleared", UserWarning)
......F.
======================================================================
FAIL: test_scatter_matrix_axis (pandas.tests.test_graphics_others.TestDataFramePlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/site-packages/pandas/tests/test_graphics_others.py", line 431, in test_scatter_matrix_axis
    frame=df, range_padding=.1)
  File "/usr/local/lib/python2.7/contextlib.py", line 24, in __exit__
    self.gen.next()
  File "/usr/local/lib/python2.7/site-packages/pandas/util/testing.py", line 2318, in assert_produces_warning
    % expected_warning.__name__)
AssertionError: Did not see expected warning of class 'UserWarning'.

----------------------------------------------------------------------
Ran 11 tests in 74.896s

FAILED (SKIP=1, failures=1)
```
#### Expected Output

I expect all tests to pass.
#### output of `pd.show_versions()`

```
INSTALLED VERSIONS
------------------
commit: None
python: 2.7.11.final.0
python-bits: 64
OS: FreeBSD
OS-release: 10.2-STABLE
machine: amd64
processor: amd64
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.18.1
nose: 1.3.7
pip: 8.0.2
setuptools: 20.0
Cython: None
numpy: 1.11.0
scipy: 0.16.1
statsmodels: None
xarray: None
IPython: None
sphinx: None
patsy: None
dateutil: 2.5.0
pytz: 2016.4
blosc: None
bottleneck: 1.0.0
tables: 3.2.2
numexpr: 2.5.2
matplotlib: 1.5.0
openpyxl: 2.3.5
xlrd: 0.9.3
xlwt: 0.7.5
xlsxwriter: 0.8.5
lxml: 3.5.0
bs4: 4.4.1
html5lib: 0.9999999
httplib2: None
apiclient: None
sqlalchemy: 0.7.10
pymysql: None
psycopg2: None
jinja2: 2.8
boto: 2.39.0
pandas_datareader: None
```
