Update ES in tests

.gitlab-ci.yml

 image: "ruby:2.3"
 services:
-  - elasticsearch:latest
+  - elasticsearch:5.1
 variables:
   ELASTICSEARCH_HOST: "elasticsearch"

Gemfile.lock

 PATH
   remote: .
   specs:
-    gitlab-elasticsearch-git (1.0.0)
+    gitlab-elasticsearch-git (1.1.0)
       activemodel (~> 4.2)
       activesupport (~> 4.2)
       charlock_holmes (~> 0.7)
@@ -22,7 +22,7 @@ GEM
       minitest (~> 5.1)
       thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
-    builder (3.2.2)
+    builder (3.2.3)
     charlock_holmes (0.7.3)
     coderay (1.1.0)
     diff-lcs (1.2.5)
@@ -95,4 +95,4 @@ DEPENDENCIES
   rugged (~> 0.24)
 BUNDLED WITH
-   1.12.5
+   1.13.6

spec/support/elastic_helper.rb

@@ -5,7 +5,7 @@ module ElasticHelper
   end
   def remove_index(index_name)
-    system("curl -XDELETE '#{elastic_url}/#{index_name}/' > /dev/null 2>&1")
+    system("curl -XDELETE '#{elastic_url}#{index_name}/' > /dev/null 2>&1")
   end
   def elastic_url