Move tox dependencies to requirements.txt/test-requirements.txt

Previously we had our requirements in two different places:
requirements/test-requirements for normal installation, and
tools/pip-requires & tools/test-requires for tox tests. Let's
unify them on a single location.

Change-Id: I3e31eeb70e7db24d87b8a7c67a427c53af814a32

test-requirements.txt

@@ -1,3 +1,6 @@
 sphinx!=1.2.0,!=1.3b1,<1.3,>=1.1.2
 oslosphinx>=2.5.0 # Apache-2.0
 reno>=0.1.1 # Apache2
+os-testr>=0.4.1 # Apache-2.0
+coverage
+hacking>=0.9.5,<0.10

tools/pip-requires

@@ -1 +0,0 @@
-docutils>=0.11

tools/test-requires

@@ -1,7 +0,0 @@
-os-testr>=0.4.1 # Apache-2.0
-coverage
-hacking>=0.9.5,<0.10
-netaddr
-pyOpenSSL
-# releasenotes
-reno>=1.8.0 # Apache-2.0

tox.ini

@@ -8,8 +8,8 @@ setenv = VIRTUAL_ENV={envdir}
          LANGUAGE=en_US:en
          LC_ALL=C
 
-deps = -r{toxinidir}/tools/pip-requires
-       -r{toxinidir}/tools/test-requires
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
 commands = /usr/bin/find . -type f -name "*.pyc" -delete
            ostestr {posargs}