Fix PyLint C0103 on `salt.utils.atomicfile`. Refs #1775.
Fix PyLint C0103 on `salt.utils.filebuffer`. Refs #1775.
Fix PyLint C0103 on `salt.utils` + PEP8. Refs #1775.
Fix PyLint C0103 on `salt.utils.verify`. Refs #1775.
Replaced OS environ checks with `salt.utils.is_windows()`.
Formatting of eclean_dist function in gentoolkit module
Fix PyLint C0103 on `salt.utils.process` + PEP8. Refs #1775.
Minor PEP-8 and enable pylint message.
Fix PyLint C0103 on `salt.utils.templates` + Some other required fixes. Refs #1775.'

* Corrected references to `template_registry` which is now `TEMPLATE_REGISTRY` on `salt.fileclient`, `salt.modules.cmdmod`, `salt.modules.cp` and `salt.moduldes.file`. Minor fixes on each of these files too.
Fix PyLint C0103 on `salt.utils.gzip_util`. Refs #1775.
Add `__ret__` to `additional-builtins` config var on `.pylintrc`. Refs #1775.
Fix PyLint C0103 on `salt.search.whoosh_search`. Refs #1775.
Double to single quotes. Refs #1775.
Fix PyLint C0103 on `salt.pillar.mongo`. Refs #1775.
Try returning a list for layman.list_local
Fix PyLint C0103 on `salt.returners.mongo_future_return`. Refs #1775.
Fix PyLint C0103 on `salt.pillar.pillar_ldap` + PEP8. Refs #1775.
Fix undefined variable on `salt.returners.redis_return`.
Fix PyLint C0103 on `salt.returners.redis_return`. Refs #1775.
Fix PyLint C0103 on `salt.returners.mongo_return`. Refs #1775.