Bump gitlab_git to rc15

Gemfile

@@ -39,7 +39,7 @@ gem "browser"
 
 # Extracting information from a git repository
 # Provide access to Gitlab::Git library
-gem "gitlab_git", '7.0.0.rc14'
+gem "gitlab_git", '7.0.0.rc15'
 
 # Ruby/Rack Git Smart-HTTP Server Handler
 gem 'gitlab-grack', '~> 2.0.0.rc2', require: 'grack'

Gemfile.lock

@@ -212,7 +212,7 @@ GEM
       mime-types (~> 1.19)
     gitlab_emoji (0.0.1.1)
       emoji (~> 1.0.1)
-    gitlab_git (7.0.0.rc14)
+    gitlab_git (7.0.0.rc15)
       activesupport (~> 4.0)
       charlock_holmes (~> 0.6)
       gitlab-linguist (~> 3.0)
@@ -701,7 +701,7 @@ DEPENDENCIES
   gitlab-grack (~> 2.0.0.rc2)
   gitlab-linguist (~> 3.0.1)
   gitlab_emoji (~> 0.0.1.1)
-  gitlab_git (= 7.0.0.rc14)
+  gitlab_git (= 7.0.0.rc15)
   gitlab_meta (= 7.0)
   gitlab_omniauth-ldap (= 1.2.0)
   gollum-lib (~> 4.0.0)