Bug 995374 - Update virtualenv to 1.11.4; r=mshal

We're trying to stay up to date on virtualenv releases so we don't fall
too far behind and so we can leverage new features, such as wheels.

This virtualenv release features upgrades to pip (1.4.1 to 1.5.4) and
setuptools (0.9.8 to 2.2). These may fix bugs people are encountering
in the wild.

Tarball obtained from
https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.11.4.tar.gz#md5=9accc2d3f0ec1da479ce2c3d1fdff06e.
the egg-info directory was removed (consistent with previous virtualenv
upgrades).

python/virtualenv/docs/conf.py

@@ -14,6 +14,8 @@
 import os
 import sys
 
+on_rtd = os.environ.get('READTHEDOCS', None) == 'True'
+
 # If your extensions are in another directory, add it here.
 sys.path.insert(0, os.path.abspath(os.pardir))
 
@@ -36,7 +38,7 @@ master_doc = 'index'
 
 # General substitutions.
 project = 'virtualenv'
-copyright = '2007-2013, Ian Bicking, The Open Planning Project, The virtualenv developers'
+copyright = '2007-2014, Ian Bicking, The Open Planning Project, PyPA'
 
 # The default replacements for |version| and |release|, also used in various
 # other places throughout the built documents.
@@ -81,8 +83,14 @@ pygments_style = 'sphinx'
 # given in html_static_path.
 #html_style = 'default.css'
 
-html_theme = 'nature'
-html_theme_path = ['_theme']
+if os.environ.get('DOCS_LOCAL'):
+    import sphinx_rtd_theme
+    html_theme = "sphinx_rtd_theme"
+    html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
+else:
+    # on RTD
+    html_theme = 'default'
+
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,