Major dependency update (#1974)

* [V3] Stop `tmp` dir showing up

* [V3] Remove requirements.txt and declare in install_requires

* Remove requirements.txt from tox.ini

* Update and pin all dependencies and sub-dependencies

* Update for breaking changes

* Reformat

* Update docs/requirements.txt and tox.ini requirements

* Add 3.7 to identifiers and travis/tox builds

* Attempt at fixing the travis build matrix

* Attempt #2

* Attempt 3

* aiohttp.ClientSession.close() -> detach() in sync code

* Add raven-aiohttp to requirements

* Fix stuff in setup.py

 - Added discord.py back into requirements list
 - Fix typo in alabaster extra requirement

Also in the Pipfile:
 - Removed allow_prereleases and explicitly pinned black, since this is the only dep we want a prerelease for.

* Update to Rapptz/discord.py@8ccb98d395

* Add proper 3.7 build in Travis

See travis-ci/travis-ci#9815

* Which version of 3.6 does Xenial install then?

* Maybe we should stop pipenv installing useless stuff

* Nevermind, back to specific minor version

* Remove lots of WET dependency stuff

* Fix egg fragment for dependency link

Pipfile

@@ -4,17 +4,9 @@ verify_ssl = true
 name = "pypi"
 
 [packages]
-"discord.py" = { git = 'git://github.com/Rapptz/discord.py', ref = '7eb918b19e3e60b56eb9039eb267f8f3477c5e17', editable = true}
-"e1839a8" = {path = ".", editable = true}
+"discord.py" = { git = 'git://github.com/Rapptz/discord.py', ref = 'rewrite', editable = true }
+"e1839a8" = { path = ".", editable = true, extras = ['mongo', 'voice'] }
 
 [dev-packages]
 tox = "*"
-pytest = "*"
-pytest-asyncio = "*"
-sphinx = ">1.7"
-sphinxcontrib-asyncio = "*"
-sphinx-rtd-theme = "*"
-black = "*"
-
-[pipenv]
-allow_prereleases = true
+"e1839a9" = { path = ".", editable = true, extras = ['docs', 'test', 'style'] }