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git-core package name is obsolete for any supported version of debian or ubuntu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git-core package name is obsolete for any supported version of debian or ubuntu.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
Merge pull request #1129 from chebee7i/wheels

Use wheels with TravisCI for NumPy, etc. Closes #1137.