gateone: add missing dependency

root@beagleboneA3-0457:~# systemctl status gateone.service
gateone.service - GateOne daemon
	  Loaded: loaded (/lib/systemd/system/gateone.service; enabled)
	  Active: failed since Tue, 24 Jan 2012 19:44:10 +0000; 1h 2min ago
	 Process: 102 ExecStart=/usr/bin/python gateone.py (code=exited, status=1/FAILURE)
	  CGroup: name=systemd:/system/gateone.service

Jan 24 19:44:10 beagleboneA3-0457 python[102]: imported = __import__(plugin, None, None, [''])
Jan 24 19:44:10 beagleboneA3-0457 python[102]: File "/var/lib/gateone/plugins/bookmarks/bookmarks.py", line 38, in <module>
Jan 24 19:44:10 beagleboneA3-0457 python[102]: import html5lib
Jan 24 19:44:10 beagleboneA3-0457 python[102]: File "/var/lib/gateone/plugins/bookmarks/dependencies/html5lib/__init__.py", line 14, in <module>
Jan 24 19:44:10 beagleboneA3-0457 python[102]: from html5parser import HTMLParser, parse, parseFragment
Jan 24 19:44:10 beagleboneA3-0457 python[102]: File "/var/lib/gateone/plugins/bookmarks/dependencies/html5lib/html5parser.py", line 25, in <module>
Jan 24 19:44:10 beagleboneA3-0457 python[102]: from treebuilders import simpletree
Jan 24 19:44:10 beagleboneA3-0457 python[102]: File "/var/lib/gateone/plugins/bookmarks/dependencies/html5lib/treebuilders/simpletree.py", line 3, in <module>
Jan 24 19:44:10 beagleboneA3-0457 python[102]: from xml.sax.saxutils import escape
Jan 24 19:44:10 beagleboneA3-0457 python[102]: ImportError: No module named xml.sax.saxutils

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>