Bump poltergeist

Gemfile

@@ -283,7 +283,7 @@ group :test do
 
   gem "capybara",           "2.18.0"
   gem "database_cleaner",   "1.6.2"
-  gem "poltergeist",        "1.17.0"
+  gem "poltergeist",        "1.18.1"
 
   gem "cucumber-api-steps", "0.14", require: false
 

Gemfile.lock

@@ -443,8 +443,8 @@ GEM
       ast (~> 2.4.0)
     pg (1.0.0)
     phantomjs (2.1.1.0)
-    poltergeist (1.17.0)
-      capybara (~> 2.1)
+    poltergeist (1.18.1)
+      capybara (>= 2.1, < 4)
       cliver (~> 0.3.1)
       websocket-driver (>= 0.2.0)
     powerpack (0.1.2)
@@ -493,7 +493,7 @@ GEM
     rack-rewrite (1.5.1)
     rack-ssl (1.4.1)
       rack
-    rack-test (1.0.0)
+    rack-test (1.1.0)
       rack (>= 1.0, < 3)
     rails (5.1.6)
       actioncable (= 5.1.6)
@@ -753,7 +753,7 @@ GEM
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.3)
     will_paginate (3.1.6)
-    xpath (3.0.0)
+    xpath (3.2.0)
       nokogiri (~> 1.8)
     yard (0.9.12)
 
@@ -827,7 +827,7 @@ DEPENDENCIES
   open_graph_reader (= 0.6.2)
   openid_connect (= 1.1.6)
   pg (= 1.0.0)
-  poltergeist (= 1.17.0)
+  poltergeist (= 1.18.1)
   pronto (= 0.9.5)
   pronto-eslint (= 0.9.1)
   pronto-haml (= 0.9.0)