Bump maint requirements

maint/requirements.txt

 alabaster==0.7.10
-appdirs==1.4.3
-args==0.1.0
-attrs==16.3.0
-Automat==0.5.0
-autopep8==1.3.1
-Babel==2.4.0
-clint==0.5.1
+attrs==17.4.0
+Automat==0.6.0
+autopep8==1.3.4
+Babel==2.5.3
+certifi==2018.1.18
+chardet==3.0.4
 constantly==15.1.0
-coverage==4.3.4
-docutils==0.13.1
-flake8==3.3.0
-imagesize==0.7.1
-incremental==16.10.1
-Jinja2==2.9.6
+coverage==4.5.1
+docutils==0.14
+flake8==3.5.0
+hyperlink==18.0.0
+idna==2.6
+imagesize==1.0.0
+incremental==17.5.0
+Jinja2==2.10
 MarkupSafe==1.0
 mccabe==0.6.1
-packaging==16.8
-pep8==1.7.0
-pkginfo==1.4.1
-pluggy==0.4.0
-py==1.4.33
-pycares==2.1.1
+packaging==17.1
+pep8==1.7.1
+pkginfo==1.4.2
+pluggy==0.6.0
+py==1.5.2
+pycares==2.3.0
 pycodestyle==2.3.1
-pycurl==7.43.0
-pyflakes==1.5.0
+pycurl==7.43.0.1
+pyflakes==1.6.0
 Pygments==2.2.0
 pyparsing==2.2.0
-pytz==2017.2
-requests==2.13.0
-requests-toolbelt==0.7.1
-six==1.10.0
+pytz==2018.3
+requests==2.18.4
+requests-toolbelt==0.8.0
+six==1.11.0
 snowballstemmer==1.2.1
-Sphinx==1.5.5
+Sphinx==1.7.1
 sphinx-rtd-theme==0.2.4
-tox==2.7.0
-twine==1.8.1
-Twisted==17.1.0
+sphinxcontrib-websupport==1.0.1
+tox==2.9.1
+tqdm==4.19.8
+twine==1.10.0
+Twisted==17.9.0
+urllib3==1.22
 virtualenv==15.1.0
-zope.interface==4.3.3
+zope.interface==4.4.3