chore(dependencies): Bump selenium-webdriver from 3.5.0 to 3.7.0 (#33)

Bumps [selenium-webdriver](https://github.com/SeleniumHQ/selenium) from 3.5.0 to 3.7.0.
- [Commits](https://github.com/SeleniumHQ/selenium/compare/selenium-3.5.0...selenium-3.7.0)

Gemfile.lock

@@ -76,7 +76,7 @@ GEM
       rack (>= 1.0.0)
       rack-test (>= 0.5.4)
       xpath (~> 2.0)
-    childprocess (0.7.1)
+    childprocess (0.8.0)
       ffi (~> 1.0, >= 1.0.11)
     concurrent-ruby (1.0.5)
     crack (0.4.3)
@@ -228,7 +228,7 @@ GEM
       sprockets (>= 2.8, < 4.0)
       sprockets-rails (>= 2.0, < 4.0)
       tilt (>= 1.1, < 3)
-    selenium-webdriver (3.5.0)
+    selenium-webdriver (3.7.0)
       childprocess (~> 0.5)
       rubyzip (~> 1.0)
     slack-notifier (2.2.2)