Merge pull request #490 from drdavella/fix-astropy-dependency

We now require astropy>=3.0

setup.cfg

@@ -49,7 +49,7 @@ edit_on_github = True
 github_project = spacetelescope/specviz
 # install_requires should be formatted as a comma-separated list, e.g.:
 # install_requires = astropy, scipy, matplotlib
-install_requires = astropy, pyqt5, pyqtgraph, qtawesome, qtpy, specutils>=0.4, click, pytest, asteval
+install_requires = astropy>=3.0, pyqt5, pyqtgraph, qtawesome, qtpy, specutils>=0.4, click, pytest, asteval
 # version should be PEP386 compatible (http://www.python.org/dev/peps/pep-0386)
 version = 0.6.dev0
 # Note: you will also need to change this in your package's __init__.py