Remove duplicate utility functions from `eth.tools.fixtures.normalization`

[pipermerriam]

What is wrong?

from: #1396 (review)

There are duplicates of some of the functions in:

• eth.tools._utils.normalization
• eth.tools.fixtures.normalization

Specifically the normalize_int but there may be others.

How can it be fixed

Audit these two modules for duplicate functions and remove the duplicates. In the case of normalize_int, the _utils one should be kept. Use your best judgement on any others that are found.

[isaacelee]

I'm going to look in to this, shouldn't be too difficult.

[glaksmono]

@isaacelee are you still working on this? Otherwise I'm considering to take a stab on it