Fix "with-deps" name in tox.ini to "with_deps"

pip 8.1.2 does not like with-deps any more

Author: lopuhin

tox.ini

@@ -14,5 +14,5 @@ commands=
     pip install -U wheel pip
     pip install numpy
     pip install scipy
-    pip install -e .[with-deps,annotation]
+    pip install -e .[with_deps,annotation]
     py.test --doctest-modules --cov=formasaurus --cov-report= {posargs: formasaurus tests}