Group tox optional dependencies

Group the additional dependencies for tox. The way they are specified
now means that the working directory is copied into /tmp 3 times, one
for each . which can cause space issues.

Also removes specifically installing requirements.txt as this will be
handled for the dependencies of .

Change-Id: Ia2c86c70f059c6352586221e13857e5bd17ae37c
Closes-Bug: #1490354

tox.ini

@@ -7,11 +7,8 @@ envlist = py27,py34,pep8,docs,genconfig
 usedevelop = True
 install_command = pip install -U {opts} {packages}
 setenv = VIRTUAL_ENV={envdir}
-deps = -r{toxinidir}/requirements.txt
-       -r{toxinidir}/test-requirements.txt
-       .[ldap]
-       .[memcache]
-       .[mongodb]
+deps = -r{toxinidir}/test-requirements.txt
+       .[ldap,memcache,mongodb]
 commands = bash tools/pretty_tox.sh '{posargs}'
 whitelist_externals = bash
 passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
@@ -19,8 +16,7 @@ passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 [testenv:py34]
 deps = -r{toxinidir}/test-requirements.txt
        nose
-       .[memcache]
-       .[mongodb]
+       .[memcache,mongodb]
 commands =
   nosetests --with-coverage --cover-package=keystone \
       keystone/tests/unit/auth/test_controllers.py \