Impacted versions:
9.0, 10.0, 11.0 (Maybe 8.0)
I don't know if it is really an expected behaviour for odoo but I like to expose it

Steps to reproduce:

1. Open an ir.cron record and change it to:
 - interval: minutes
 - next execution date: now + 1 minute

2. Open the odoo server log

Note: I'm using workers=3 but I don't know if there is possible to reproduce it without workers.

Current behavior:

You will see for each cron execution the following output
```txt
...
2018-06-01 16:18:33,432 20686 INFO 333561-11-0-42aff9-all odoo.modules.registry: Invalidating all model caches after database signaling.
...
2018-06-01 16:17:21,527 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: loading 1 modules...
2018-06-01 16:17:21,535 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: 1 modules loaded in 0.01s, 0 queries
2018-06-01 16:17:21,594 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: loading 206 modules...
2018-06-01 16:17:21,718 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: 206 modules loaded in 0.12s, 0 queries
2018-06-01 16:17:21,989 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: Modules loaded.
```

Expected behavior:
 - Review if the method that run from the cron really requires a invalidate cache and delete all registries.
 - Disable "minutes" for cron interval because all cache are deleted then is not valid use them.

Video/Screenshot link (optional):

 - [![IMAGE ALT TEXT HERE](https://img.youtube.com/vi/Be4FIeQjgjk/0.jpg)](https://youtu.be/Be4FIeQjgjk)
openerp/service/server.py
""" werkzeug Threaded WSGI Server patched to allow reusing a listen socket
    given by the environement, this is used by autoreload to keep the listen
    socket open when a reload happens.
    """
    def __init__(self, host, port, app):
        super(ThreadedWSGIServerReloadable, self).__init__(host, port, app,
                                                           handler=RequestHandler)
    def server_bind(self):
        SD_LISTEN_FDS_START = 3
        if os.environ.get('LISTEN_FDS') == '1' and os.environ.get('LISTEN_PID') == str(os.getpid()):
            self.reload_socket = True
            self.socket = socket.fromfd(SD_LISTEN_FDS_START, socket.AF_INET, socket.SOCK_STREAM)
            _logger.info('HTTP service (werkzeug) running through socket activation')
        else:
            self.reload_socket = False
            super(ThreadedWSGIServerReloadable, self).server_bind()
            _logger.info('HTTP service (werkzeug) running on %s:%s', self.server_name, self.server_port)
    def server_activate(self):
        if not self.reload_socket:
            super(ThreadedWSGIServerReloadable, self).server_activate()
class FSWatcher(object):
    def __init__(self):
        self.observer = Observer()
        for path in openerp.modules.module.ad_paths:
            _logger.info('Watching addons folder %s', path)
            self.observer.schedule(self, path, recursive=True)
    def dispatch(self, event):