Move requirements for docs and testing into extras

.readthedocs.yml

@@ -1,3 +1,5 @@
-requirements_file: docs/requirements.txt
 python:
   version: 3
+  extra_requirements:
+    - docs
+  pip_install: true

docs/requirements.txt

@@ -1,4 +0,0 @@
-.
-sphinx
-jaraco.packaging>=3.2
-rst.linker>=1.9

setup.py

@@ -27,6 +27,15 @@ params = dict(
 	install_requires=[
 	],
 	extras_require={
+		'testing': [
+			'pytest>=2.8',
+			'pytest-sugar',
+		],
+		'docs': [
+			'sphinx',
+			'jaraco.packaging>=3.2',
+			'rst.linker>=1.9',
+		],
 	},
 	setup_requires=[
 		'setuptools_scm>=1.15.0',

tests/requirements.txt

@@ -1,2 +0,0 @@
-pytest >= 2.8
-pytest-sugar

tox.ini

@@ -1,6 +1,4 @@
 [testenv]
-deps =
-	-rtests/requirements.txt
-
 commands = py.test {posargs}
 usedevelop = True
+extras = testing