Test Failures on OS X El Capitan

Here are the errors I'm seeing:

```
======================================================================
ERROR: test_option_quotes (quantlib.test.test_notebooks.NoteBooksTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/jianliu/git_projects/lendingclub-explore/src/pyql/quantlib/test/test_notebooks.py", line 162, in test_option_quotes
option_data_frame = pandas.core.common.load(
AttributeError: module 'pandas.core.common' has no attribute 'load'

======================================================================
ERROR: test_at (quantlib.test.test_schedule.ScheduleMethodTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/jianliu/git_projects/lendingclub-explore/src/pyql/quantlib/test/test_schedule.py", line 49, in setUp
self.convention, self.termination_convention, self.rule
File "quantlib/time/schedule.pyx", line 49, in quantlib.time.schedule.Schedule.__init__ (quantlib/time/schedule.cpp:1742)
self._thisptr = new _schedule.Schedule(
RuntimeError: undecidable comparison between 4W and 1M
======================================================================
ERROR: test_dates (quantlib.test.test_schedule.ScheduleMethodTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/jianliu/git_projects/lendingclub-explore/src/pyql/quantlib/test/test_schedule.py", line 49, in setUp
self.convention, self.termination_convention, self.rule
File "quantlib/time/schedule.pyx", line 49, in quantlib.time.schedule.Schedule.__init__ (quantlib/time/schedule.cpp:1742)
self._thisptr = new _schedule.Schedule(
RuntimeError: undecidable comparison between 4W and 1M

======================================================================
ERROR: test_iter_dates (quantlib.test.test_schedule.ScheduleMethodTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/jianliu/git_projects/lendingclub-explore/src/pyql/quantlib/test/test_schedule.py", line 49, in setUp
self.convention, self.termination_convention, self.rule
File "quantlib/time/schedule.pyx", line 49, in quantlib.time.schedule.Schedule.__init__ (quantlib/time/schedule.cpp:1742)
self._thisptr = new _schedule.Schedule(
RuntimeError: undecidable comparison between 4W and 1M

======================================================================
ERROR: test_previous_next_reference_date (quantlib.test.test_schedule.ScheduleMethodTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/jianliu/git_projects/lendingclub-explore/src/pyql/quantlib/test/test_schedule.py", line 49, in setUp
self.convention, self.termination_convention, self.rule
File "quantlib/time/schedule.pyx", line 49, in quantlib.time.schedule.Schedule.__init__ (quantlib/time/schedule.cpp:1742)
self._thisptr = new _schedule.Schedule(
RuntimeError: undecidable comparison between 4W and 1M

======================================================================
ERROR: test_size (quantlib.test.test_schedule.ScheduleMethodTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/jianliu/git_projects/lendingclub-explore/src/pyql/quantlib/test/test_schedule.py", line 49, in setUp
self.convention, self.termination_convention, self.rule
File "quantlib/time/schedule.pyx", line 49, in quantlib.time.schedule.Schedule.__init__ (quantlib/time/schedule.cpp:1742)
self._thisptr = new _schedule.Schedule(
RuntimeError: undecidable comparison between 4W and 1M

----------------------------------------------------------------------
```

The pandas issue seems to be because `pandas.core.common.load` was deprecated or removed by some point (I'm running pandas=0.17).

As for quantlib, I'm using a fresh build against quantlib HEAD as of today. Everything is compiled using clang against libstdc++ on El Capitan.

I built PyQL using the following:
1. `pip install -e git+https://github.com/enthought/pyql.git#egg=pyql`
2. Edit `setup.py` to point to right paths -- I'm building against Boost 1.59.0 source
3. `make clean && make build && make tests`