Merge pull request #19 from josePhoenix/master

Improve robustness of setup.py in the absence of certain dependencies
Make pylab import explicit, specify image.origin lower in notebook
Improve tutorial notebook additions formatting
minor: typo fix in install docs
add test for unicode filternames; see https://github.com/mperrin/webbpsf/issues/18
Merge pull request #22 from josePhoenix/master

Pretty up the last plot in the example notebook
ThinLens updated to use explicit radius argument (WIP)
Merge pull request #25 from josePhoenix/thinlens_update

ThinLens update to use explicit radius argument
Fix meters/microns units issue with NIRCam weak lenses
  (as yet untested, since needs uncommitted poppy changes, but this is
   so straightforward I am very confident in this fix.)
Remove pyfits imports, replace with astropy.io.fits
Merge pull request #26 from josePhoenix/remove_pyfits_tests

Remove pyfits imports in test suite, replace with astropy.io.fits
Merge branch 'master' into wfirst

Conflicts:
	.gitignore
	webbpsf/webbpsf_core.py