Not deepcopying a function---gives us IronPython support.
Add try/except clause and treat IronPython separately.
Attempt at fixing system site-packages issue with TravisCI.
Begin testing Python 3.4 as well.
Merge pull request #1130 from chebee7i/ssp

.travis.yml updates
Merge branch 'master' into nocopyfunc
Merge pull request #1128 from chebee7i/nocopyfunc

Fix for IronPython and types.FunctionType. Closes #949 #1127
Remove deprecated --use-mirrors in pip command.
Merge pull request #1132 from chebee7i/coveralls

Remove deprecated --use-mirrors in pip command.
Use symmetric eigen solver in laplacian_spectrum
Merge pull request #1133 from ysitu/eigvalsh

Use symmetric eigen solver in laplacian_spectrum
git-core package name is obsolete for any supported version of debian or ubuntu
Merge pull request #1136 from alis0nc/master

git-core package name is obsolete for any supported version of debian or ubuntu. Closes #1135
Rework .travis.yml to use wheels.
Disable TravisCI email notifications.
Add handy hyperlink from tutorial to DiGraph class
Merge pull request #1139 from matt-hickford/patch-1

Add handy hyperlink from tutorial to DiGraph class
Add pygraphviz to .travis.yml
Update test_threshold.py

Fixes #1140
Install pygraphviz only for 2.x