can not run pandas unit tests without x11 connection
I am working on automating the testing of conda environments that include pandas. I am unable to run the tests if I do not have a x11 connection setup correctly. Example:
```python
psdev105: ~ $ python -c "import pandas; pandas.test('fast',verbose=10)"
Running unit tests for pandas
pandas version 0.19.1
numpy version 1.11.2
pandas is installed in /reg/g/psdm/sw/conda/inst/miniconda2-dev-rhel6/envs/ana-1.0.6/lib/python2.7/site-packages/pandas
Python version 2.7.12 |Continuum Analytics, Inc.| (default, Jul  2 2016, 17:42:40) [GCC 4.4.7 20120313 (Red Hat 4.4.7-1)]
nose version 1.3.7
nose.config: INFO: Ignoring files matching ['^\\.', '^_', '^setup\\.py$']
X11 connection rejected because of wrong authentication.
: cannot connect to X server localhost:15.0
```
Are there a set of tests I can run that do not include a x11 connection?

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

<details>
(ana-1.0.6) psdev105: ~ $ python -c "import pandas; pandas.show_versions()"

INSTALLED VERSIONS
------------------
commit: None
python: 2.7.12.final.0
python-bits: 64
OS: Linux
OS-release: 2.6.32-504.16.2.el6.x86_64
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: C
LOCALE: None.None

pandas: 0.19.1
nose: 1.3.7
pip: 9.0.1
setuptools: 27.2.0
Cython: 0.25.1
numpy: 1.11.2
scipy: 0.18.1
statsmodels: None
xarray: 0.8.2
IPython: 5.1.0
sphinx: 1.4.8
patsy: None
dateutil: 2.5.3
pytz: 2016.7
blosc: None
bottleneck: 1.1.0
tables: 3.3.0
numexpr: 2.6.1
matplotlib: 1.5.1
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: 1.1.4
pymysql: None
psycopg2: None
jinja2: 2.8
boto: 2.43.0
pandas_datareader: None
</details>
