Create requests-async based TestClient, remove aiohttp dependency, drop Python 3.5

Update all tests to be compatible with requests-async
Cleanup testing client changes with black and isort
Remove Python 3.5 and other meta doc cleanup
rename pyproject and fix pep517 error
Add black config to tox.ini
Cleanup tests and remove aiohttp
tox.ini change for easier development commands
Remove aiohttp from changelog and requirements
Cleanup imports and Makefile

tox.ini

@@ -1,24 +1,25 @@
 [tox]
-envlist = py35, py36, py37, {py35,py36,py37}-no-ext, lint, check
+envlist = py36, py37, {py36,py37}-no-ext, lint, check
 
 [testenv]
 usedevelop = True
 setenv =
-    {py35,py36,py37}-no-ext: SANIC_NO_UJSON=1
-    {py35,py36,py37}-no-ext: SANIC_NO_UVLOOP=1
+    {py36,py37}-no-ext: SANIC_NO_UJSON=1
+    {py36,py37}-no-ext: SANIC_NO_UVLOOP=1
 deps =
     coverage
     pytest==4.1.0
     pytest-cov
     pytest-sanic
     pytest-sugar
-    aiohttp>=2.3,<=3.2.1
+    httpcore==0.1.1
+    requests-async==0.4.0
     chardet<=2.3.0
     beautifulsoup4
     gunicorn
     pytest-benchmark
 commands =
-    pytest tests --cov sanic --cov-report= {posargs}
+    pytest {posargs:tests --cov sanic}
     - coverage combine --append
     coverage report -m
     coverage html -i
@@ -31,7 +32,7 @@ deps =
 
 commands =
     flake8 sanic
-    black --check --verbose sanic
+    black --config ./.black.toml --check --verbose sanic
     isort --check-only --recursive sanic
 
 [testenv:check]