Make all linting tests use upper-constraints

As per [1] all linting tests can now use upper-constraints. This patch
removes all instances of the install_command override relating to lint
testing which were needed to negate the use of upper-constraints.

The tox-based functional test configuration is removed as it never
worked and is thus unused.

[1] http://lists.openstack.org/pipermail/openstack-dev/2016-August/101474.html

Change-Id: Ibe5bf428d3674291e7faf4eccac9a221ebd27e7d

tox.ini

@@ -39,22 +39,12 @@ commands=
 extensions = .rst
 
 [testenv:releasenotes]
-# NOTE(sdague): this target does not use constraints because
-# upstream infra does not yet support it. Once that's fixed, we can
-# drop the install_command.
-install_command =
-    pip install -U --force-reinstall {opts} {packages}
 commands =
     sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 
 # environment used by the -infra templated docs job
 [testenv:venv]
-# NOTE(jaegerandi): this target does not use constraints because
-# upstream infra does not yet support it. Once that's fixed, we can
-# drop the install_command.
-install_command =
-    pip install -U --force-reinstall {opts} {packages}
 commands =
     {posargs}
 
@@ -174,16 +164,3 @@ commands =
     {[testenv:ansible-syntax]commands}
     {[testenv:inventory]commands}
     {[testenv:docs]commands}
-
-
-[testenv:functional]
-# NOTE(odyssey4me): this target fails with the default install_command
-# due to the lack of an upper-constraints.txt file in the repo. We
-# do not want or need the file in-repo, nor do we want anything
-# installed into the tox venv for this target, so we override both
-# the install_command and the deps.
-install_command =
-    pip install -U --force-reinstall {opts} {packages}
-deps =
-commands =
-    sudo {toxinidir}/scripts/gate-check-commit.sh