Added CI_SERVER* environment variables to build process.

The environment variable CI_SERVER can be used by the build process to
switch some specific CI configuration, like this for example:
```ruby
require 'rspec/retry'
RSpec.configure do |config|
  config.default_retry_count = 3 if ENV['CI_SERVER']
end
```
The CI_SERVER_* variables were added for completeness.

app/views/layouts/application.html.haml

@@ -11,7 +11,7 @@
     .navbar.navbar-fixed-top.navbar-ci
       .navbar-inner
         .container-fluid
-          = link_to 'GitLab CI', root_path, class: "brand"
+          = link_to GitlabCi::Name, root_path, class: "brand"
           %ul.nav
             - if current_user
               %li
@@ -38,7 +38,7 @@
     .right
       .padded
         %p.light
-          GitLab CI
+          = GitlabCi::Name
           %span= GitlabCi::Version
           %small= GitlabCi::Revision

config/initializers/1_app.rb

 module GitlabCi
+  Name = "GitLab CI"
   Version = File.read(Rails.root.join("VERSION"))
   Revision = `git log --pretty=format:'%h' -n 1`
 end

lib/runner.rb

@@ -84,6 +84,12 @@ class Runner
     @process.environment['BUNDLE_GEMFILE'] = File.join(path, 'Gemfile')
     @process.environment['BUNDLE_BIN_PATH'] = ''
     @process.environment['RUBYOPT'] = ''
+
+    @process.environment['CI_SERVER'] = 'yes'
+    @process.environment['CI_SERVER_NAME'] = GitlabCi::Name
+    @process.environment['CI_SERVER_VERSION'] = GitlabCi::Version
+    @process.environment['CI_SERVER_REVISION'] = GitlabCi::Revision
+
     @process.environment['CI_BUILD_REF'] = build.ref
     
     @process.start