Converge requirements into a single file

readthedocs wants a single requirements file and since the doc
requirements are small it seems reasonable to merge the
requirement files.

doc-requirements.txt

@@ -1,2 +0,0 @@
-sphinx
-sphinxcontrib-trio

requirements.txt

@@ -28,5 +28,6 @@ python-swiftclient
 tenacity
 distro-info
 paramiko
-
-
+# Documentation requirements
+sphinx
+sphinxcontrib-trio

tox.ini

@@ -11,11 +11,11 @@ commands = nosetests {posargs} {toxinidir}/unit_tests
 
 [testenv:py3]
 basepython = python3
-deps = -r{toxinidir}/test-requirements.txt
+deps = -r{toxinidir}/requirements.txt
 
 [testenv:pep8]
 basepython = python3
-deps = -r{toxinidir}/test-requirements.txt
+deps = -r{toxinidir}/requirements.txt
 commands = flake8 {posargs} zaza unit_tests
 
 [testenv:venv]
@@ -28,6 +28,5 @@ ignore = E402,E226
 basepython = python3
 changedir = doc/source
 deps =
-    -r{toxinidir}/test-requirements.txt
-    -r{toxinidir}/doc-requirements.txt
+    -r{toxinidir}/requirements.txt
 commands = sphinx-build -W -b html -d {toxinidir}/doc/build/doctrees . {toxinidir}/doc/build/html