Change filenames and namespaces

[blogle]

We need to eliminate future confusion and safely go through renaming all zipline files.

I would like an import convention similar to numpy or pandas ie.

some permutation of
import alephnull as a0
import anaught as an

whatever best complies with PEP, and doesn't interfere with builtins.

[erikness]

Partially done. Bindings to import variables aren't changed yet, but the zipline package has been renamed AlephNull. (this means you'll still have a few "import alephnull.utils.math as zp_math" floating around)

See 14f115e for more details.