Use slapos provided networkcached buildout.

As older versions of slapos.core will ignore slapos:buildout switch it is safe
to direct them to unexisting one.

New slapos profiles are generating buildout_networkache in self location, so as
already all parameters are hardocded, use such path directly.

slapos/builder/__init__.py

@@ -177,7 +177,9 @@ def run(config):
             'template/slapos.cfg.in').read() % dict(
               computer_id=config.computer_id, master_url=config.master_url,
               key_file=key_file, cert_file=cert_file,
-              certificate_repository_path=certificate_repository_path
+              certificate_repository_path=certificate_repository_path,
+              buildout=os.path.join('/opt', 'slapos', 'bin',
+                'buildout_networkache')
             ))
 
       hostname_path = os.path.normpath('/'.join([mount_dir_path,

slapos/builder/template/slapos.cfg.in

@@ -6,6 +6,7 @@ computer_id = %(computer_id)s
 key_file = %(key_file)s
 cert_file = %(cert_file)s
 certificate_repository_path = %(certificate_repository_path)s
+buildout = %(buildout_path)
 
 [slapformat]
 computer_xml = /opt/slapos/slapos.xml