allow to download full zip updates

states are now reflected: downloading, downloaded, installed

i am using a threadpoolexecuter and workqueues, which allow to download
multiple updates at once, if someone wants to.

while downloading a notification is present, for each download.
pressing on these notifications cause the update list to open, where a
download can be aborted if wanted.

downloaded updates can be deleted or installed.

before installing we check the md5sum of the downloaded file with the
provided md5sum to be sure the download is not corrupt

if the md5sum does not match, show a warning, else let the user reboot
and install.

NOTE: the notification bypasses this check

Change-Id: I00d83606d20f0582ac530285ad8900fe35a70fbe
make the simple card a bit more useful

Change-Id: Ifdb3e907f841954b47ad09cf3e2a74a0e8db363e
allow to refresh via action bar too, cross fade list with a progress bar

Change-Id: Ief48b1fa51e871bdee7882345721d54636f41b5b