updating: set timer timeout to 1 min & check time difference

this allows for detection of suspend/hibernation & resume
status icon: add a new state & icon: 'need user input', used to confirm transactions
refactor YumServer: make YumBase an attribute

this *should* not change any behaviour.
makes it possible to recreate the YumBase object (to recreate cached lists)
recreate YumBase when searching for updates to update the cache

this also introduces a minimum interval of 60 seconds for recreating
YumBase, to avoid frequent recreation (usually a search for updates
is followed by a search of obsoletes which both would trigger a
recreation of YumBase)
save and restore applied options when recreating YumBase
show the main window after a transaction only if 'do you want to exit?' is shown
Merge branch 'master' into update_checking

Conflicts:
	src/yumexgui/__init__.py
YumServer: simplify creation of list of enabled repos
Merge branch 'master' into update_checking
fix: set dsCallback properly
fix YumexRPMCallback: use yumbase attribute
Merge pull request #10 from bkueng/update_checking

Update checking working