Update browser gem to version 0.8.0 for IE11 support

Closes #1775

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
 
 v 7.12.0 (unreleased)
+  - Update browser gem to version 0.8.0 for IE11 support (Stan Hu)
   - Fix timeout when rendering file with thousands of lines.
   - Add "Remember me" checkbox to LDAP signin form.
   - Don't notify users mentioned in code blocks or blockquotes.

Gemfile

@@ -30,7 +30,7 @@ gem 'rqrcode-rails3'
 gem 'attr_encrypted', '1.3.4'
 
 # Browser detection
-gem "browser"
+gem "browser", '~> 0.8.0'
 
 # Extracting information from a git repository
 # Provide access to Gitlab::Git library

Gemfile.lock

@@ -75,7 +75,7 @@ GEM
       ruby_parser (~> 3.5.0)
       sass (~> 3.0)
       terminal-table (~> 1.4)
-    browser (0.7.2)
+    browser (0.8.0)
     builder (3.2.2)
     byebug (3.2.0)
       columnize (~> 0.8)
@@ -680,7 +680,7 @@ DEPENDENCIES
   binding_of_caller
   bootstrap-sass (~> 3.0)
   brakeman
-  browser
+  browser (~> 0.8.0)
   byebug
   cal-heatmap-rails (~> 0.0.1)
   capybara (~> 2.2.1)