Add TensorFlow to lambda-packages

[jbencook]

This adds a TensorFlow tarball and build script as mentioned in #31. I've got a simple smoke test running here. I plan to write a more useful TensorFlow example in Zappa as soon as I have a little time.

[Miserlou]

Excellent!

But, can I ask - did the manylinux version of Tensorflow not work out of the box? It seems there are manylinux wheels available on PyPI: https://pypi.python.org/pypi/tensorflow

So, it should just automatically use those. Is this package optimized further?

[jbencook]

Yeah it could be user error, but I couldn't get the manylinux version to work.

[Miserlou]

Can you be more specific about how it didn't work?

[jbencook]

Hm... I can try to repro later, but I'm pretty sure the import tensorflow as tf line threw an error.

[brunoalano]

@Miserlou I checked that, and it's because tensorflow has runtime dependency, and throws that error. But I think that this PR it's to heavy for lambda-packages.

Maybe we should think something about #36

[matthewp]

Going to update this to use import.meta.env.astro instead of static for right now.