Revert "restore requirements"

This reverts commit aeb573e.

requirements.txt

@@ -1,24 +1,2 @@
-alabaster==0.7.10
-arrow==0.10.0
-Babel==2.5.0
-certifi==2017.7.27.1
-chardet==3.0.4
-click==6.7
-docutils==0.14
-git-ext==0.3.5
-idna==2.6
-imagesize==0.7.1
-Jinja2==2.9.6
-MarkupSafe==1.0
-Pygments==2.2.0
-python-dateutil==2.6.1
-pytz==2017.2
-PyYAML==3.12
-requests==2.18.4
-six==1.10.0
-snowballstemmer==1.2.1
-Sphinx==1.6.3
-sphinx-rtd-theme==0.2.4
-sphinxcontrib-websupport==1.0.1
-typing==3.6.2
-urllib3==1.22
+sphinx_rtd_theme
+sphinx