Fix build

[ocefpaf]

Ping @lbdreyer and @dkillick this is a workaround. I am working on getting this resolved so everything can be unpinned and back to normal.

[ocefpaf]

Travis-CI is failing with:

===== testing package: nc_time_axis-1.0.1-py27_0 =====
import: 'nc_time_axis'
Traceback (most recent call last):
  File "/Users/travis/miniconda/conda-bld/nc_time_axis_1488890050956/test_tmp/run_test.py", line 27, in <module>
    import nc_time_axis
  File "/Users/travis/miniconda/conda-bld/nc_time_axis_1488890050956/_t_env/lib/python2.7/site-packages/nc_time_axis/__init__.py", line 15, in <module>
    import netcdftime
  File "/Users/travis/miniconda/conda-bld/nc_time_axis_1488890050956/_t_env/lib/python2.7/site-packages/netcdftime/__init__.py", line 1, in <module>
    from .netcdftime import utime, JulianDayFromDate, DateFromJulianDay
  File "/Users/travis/miniconda/conda-bld/nc_time_axis_1488890050956/_t_env/lib/python2.7/site-packages/netcdftime/netcdftime.py", line 14, in <module>
    from ._datetime import datetime
ImportError: dlopen(/Users/travis/miniconda/conda-bld/nc_time_axis_1488890050956/_t_env/lib/python2.7/site-packages/netcdftime/_datetime.so, 2): Library not loaded: @rpath/libmfhdf.0.dylib
  Referenced from: /Users/travis/miniconda/conda-bld/nc_time_axis_1488890050956/_t_env/lib/libnetcdf.11.dylib
  Reason: image not found
TESTS FAILED: nc_time_axis-1.0.1-py27_0

That looks like a problem with defaults libnetcdf and hdf4 (I did see some people reporting this but I though it was resolved. I don't really know what is going on because that problem does not exists on conda-forge.)

[ocefpaf]

OK. AppVeyor it green. After this is merged I will try a few tests to see if I can get Travis-CI working too.