[UI] Fix non-unique hostlist host_id

Use a sha1 of time.time() can result in identical host_id. This was
evident with Travis tests randomly failing due to host_id collision
returning the wrong host details.

Using uuid4 to generate a random UUID in hex form should fix this issue.

ChangeLog

@@ -8,6 +8,7 @@
     there to allow acting upon them.
     * Enforced the use of the "deluge.plugins" namespace to reduce package
     names clashing beetween regular packages and deluge plugins.
+    * Fix potential for host_id collision when creating hostlist entries.
 
 ==== Core ====
     * Make the distinction between adding to the session new unmanaged torrents

deluge/ui/hostlist.py

@@ -11,8 +11,7 @@ from __future__ import unicode_literals
 
 import logging
 import os
-import time
-from hashlib import sha1
+import uuid
 from socket import gaierror, gethostbyname
 
 from twisted.internet import defer
@@ -31,7 +30,7 @@ LOCALHOST = ('127.0.0.1', 'localhost')
 
 def default_hostlist():
     """Create a new hosts key for hostlist with a localhost entry"""
-    host_id = sha1(str(time.time()).encode('utf8')).hexdigest()
+    host_id = uuid.uuid4().hex
     username, password = get_localhost_auth()
     return {'hosts': [(host_id, DEFAULT_HOST, DEFAULT_PORT, username, password)]}
 
@@ -132,7 +131,7 @@ class HostList(object):
 
         validate_host_info(hostname, port)
         self.check_info_exists(hostname, port, username)
-        host_id = sha1(str(time.time())).hexdigest()
+        host_id = uuid.uuid4().hex
         self.config['hosts'].append((host_id, hostname, port, username, password))
         self.config.save()
         return host_id