[V3] Add pipenv files (#1642)

* Add pipenv files

* Pipfile updates

* Update sphinx version

Pipfile

@@ -0,0 +1,15 @@
+[[source]]
+url = "https://pypi.org/simple"
+verify_ssl = true
+name = "pypi"
+
+[packages]
+"discord.py" = { git = 'git://github.com/Rapptz/discord.py', ref = 'rewrite', editable = true}
+"e1839a8" = {path = ".", editable = true}
+
+[dev-packages]
+pytest = "*"
+pytest-asyncio = "*"
+sphinx = ">1.7"
+sphinxcontrib-asyncio = "*"
+sphinx-rtd-theme = "*"