Perhaps a seaborn problem

When attempting @pyimport seaborn, I am told that Python is not installed as a framework. But, it certainly is installed as a framework. PyPlot works. Plots with pyplot backend works. I can pyimport Matplotlib and sys--and probably lots of other Python packages. I'd like to use seaborn, but I can survive without it.

Messages follow and examples of importing Matplotlib and sys (to show the Python version that is invoked):

```
julia> using PyCall

julia> @pyimport seaborn
ERROR: PyError (PyImport_ImportModule)
RuntimeError("Python is not installed as a framework. The Mac OS X backend will not be able to function correctly if Python is not installed as a framework. See the Python documentation for more information on installing Python as a framework on Mac OS X. Please either reinstall Python as a framework, or try one of the other backends. If you are using (Ana)Conda please install python.app and replace the use of 'python' with 'pythonw'. See 'Working with Matplotlib on OSX' in the Matplotlib FAQ for more information.")
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/seaborn/__init__.py", line 6, in
from .rcmod import *
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/seaborn/rcmod.py", line 5, in
from . import palettes, _orig_rc_params
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/seaborn/palettes.py", line 12, in
from .utils import desaturate, set_hls_values, get_color_cycle
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/seaborn/utils.py", line 11, in
import matplotlib.pyplot as plt
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/matplotlib/pyplot.py", line 115, in
_backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/matplotlib/backends/__init__.py", line 62, in pylab_setup
[backend_name], 0)
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/matplotlib/backends/backend_macosx.py", line 17, in
from matplotlib.backends import _macosx

Stacktrace:
[1] pyimport(::String) at /Users/lewis/.julia/packages/PyCall/akNFy/src/PyCall.jl:479
[2] top-level scope at /Users/lewis/.julia/packages/PyCall/akNFy/src/PyCall.jl:529

julia> @pyimport matplotlib

julia> @pyimport sys

julia> sys.version
"3.7.0 (default, Jul 23 2018, 20:22:55) \n[Clang 9.1.0 (clang-902.0.39.2)]"

julia>
```

Start with the @pyimport path in PyCall.jl at lines 479 and 529, then reproduce the seaborn import using the Python and matplotlib versions shown in the report. Compare it with the successful matplotlib and sys imports; done means identifying whether PyCall or the macOS matplotlib backend causes the framework error and documenting or correcting that behavior.

索引モデルが issue の本文から書いたものです。