Use instance variables in templates

The use of ruby methods to access manifest variables has been
deprecated and will be removed in puppet 4. This patch updates the
template to use ruby instance variables to access manifest
variables.

Change-Id: I332076adbd8a1c4d0259e0711e16579a460f7728

templates/gerritbot.config.erb

@@ -1,14 +1,14 @@
 [ircbot]
-nick=<%= nick %>
-pass=<%= password %>
-server=<%= server %>
+nick=<%= @nick %>
+pass=<%= @password %>
+server=<%= @server %>
 port=6667
 channel_config=/etc/gerritbot/channel_config.yaml
 lockfile=/var/run/gerritbot/gerritbot.pid
 log_config=/etc/gerritbot/logging.config
 
 [gerrit]
-user=<%= user %>
+user=<%= @user %>
 key=/home/gerrit2/.ssh/gerritbot_rsa
-host=<%= vhost_name %>
+host=<%= @vhost_name %>
 port=29418