Improve performance of zabbix_host

Before this commit, every template added to a host genarated addtional 5
API calls. This isn't needed as we can get all required information by
only one API call.

Fixes #558.

lib/puppet/provider/zabbix.rb

@@ -21,7 +21,16 @@ def self.create_connection(zabbix_url, zabbix_user, zabbix_pass, apache_use_ssl)
   # Check if host exists. When error raised, return false.
   def self.check_host(host, zabbix_url, zabbix_user, zabbix_pass, apache_use_ssl)
     zbx = create_connection(zabbix_url, zabbix_user, zabbix_pass, apache_use_ssl)
-    zbx.hosts.get_id(host: host)
+    zbx.query(
+      method: 'host.get',
+      params: {
+        filter: {
+          'host' => [host]
+        },
+        selectParentTemplates: ['host'],
+        output: ['host']
+      }
+    )
   rescue Puppet::ExecutionFailure
     false
   end

lib/puppet/provider/zabbix_host/ruby.rb

@@ -89,12 +89,22 @@ def exists?
 
     templates = [templates] unless templates.is_a?(Array)
 
-    res = []
-    res.push(self.class.check_host(host, zabbix_url, zabbix_user, zabbix_pass, apache_use_ssl))
-    templates.each do |template|
-      res.push(self.class.check_template_in_host(host, template, zabbix_url, zabbix_user, zabbix_pass, apache_use_ssl))
+    host = self.class.check_host(host, zabbix_url, zabbix_user, zabbix_pass, apache_use_ssl)
+    if host.any?
+      template_ids   = host[0]['parentTemplates'].map { |x| x['templateid'] }
+      template_names = host[0]['parentTemplates'].map { |x| x['host'] }
+      res = []
+      templates.each do |template|
+        if self.class.a_number?(template)
+          res.push(template_ids.include?(template))
+        else
+          res.push(template_names.include?(template))
+        end
+      end
+      res.all?
+    else
+      false
     end
-    res.all?
   end
 
   def destroy