Consider reorganizing file layout to shorten path lengths

Describe the bug
The current package includes path names upwards of 150 characters such as default_8bit_cluster_preserve_quantize_scheme.py which are in turn relatively short files deep in a hierarchy. On Windows, the default limitation for paths is 260 characters as defined by MAX_PATH. While it is possible to modify this on a per-call basis, by default the Python ecosystem's tooling does not make this process simple for end users and there are a variety of tools still limited to the 260 character MAX_PATH. When you combine the path lengths of this repository with a location in a users' profile such as C:\Users\person-fullname\AppData\Local\Python\environments\deep-learning-environment\Lib\site-packages the limit can be exceeded.

Motivation
I work in a context where users can create environments in arbitrary locations and we want to use this package, the workaround we've found for the time being is to repack this repository as a Python egg and inject that into the environment at runtime, but would prefer to be able to use it as a direct Python dependency. Note that this limitation is specific to Windows, fortunately MacOS defaults to a MAXPATHLEN of 1024 and Linux values are typically 1024 or higher.

System information

TensorFlow version (installed from source or binary): All versions

TensorFlow Model Optimization version (installed from source or binary): All versions, specifically found working with v0.7.3.