Universal wheels

[joshfriend]

Right now, there is only a py2 wheel being released. This PR will cause bdist_wheel to build a universal py2.py3 wheel instead. It also tells the Travis release task to upload the wheel to PyPI in addition to the sdist which is the only one uploaded by default

[corydolphin]

Awesome, this is great.

Thanks so much for your help @joshfriend! Once tests pass, I'll merge it up.

[corydolphin]

Also, since you appear to be a Travis wizard, any ideas why 2.1.3 did not build on Travis? I'm out of ideas.

[coveralls]

Changes Unknown when pulling 8703b11 on joshfriend:universal-wheels into * on corydolphin:master*.

[coveralls]

Changes Unknown when pulling 8703b11 on joshfriend:universal-wheels into * on corydolphin:master*.

[coveralls]

Changes Unknown when pulling 8703b11 on joshfriend:universal-wheels into * on corydolphin:master*.

[coveralls]

Changes Unknown when pulling 8703b11 on joshfriend:universal-wheels into * on corydolphin:master*.

[coveralls]

Changes Unknown when pulling 8703b11 on joshfriend:universal-wheels into * on corydolphin:master*.

[coveralls]

Changes Unknown when pulling 8703b11 on joshfriend:universal-wheels into * on corydolphin:master*.

[joshfriend]

Wow, chill out coveralls! ;)

Tag 2.1.3 is commit a2188d0:

$ git show-ref --tags | grep 2.1.3
a2188d0aeb02c03ba8e71d004acd68699bba82ed refs/tags/2.1.3

However, I don't see any travis builds for that commit sha. There are 4 builds in the log that have the a commit message related to #150, but none of those is for the tagged commit. Since that PR has only 2 commits on it, I suspect some merging and force pushing caused travis to miss building that commit somehow?