construct the foother in defaults.php so that we use always the same footer

Conflicts:

	settings/templates/admin.php
check for updates only in the community edition
lib/defaults.php should only contain the default strings and read the other strings directly from the theme
remove unneeded if condition
make mail footer aware of different themes

Conflicts:

	lib/mail.php
logo claim added
add logo claim to defaults.php
set default logo claim to ''
Merge branch 'master' of github.com:owncloud/core