fix return value of OC_Util::isinternetconnectionworking()
move check if internet connection is disabled on purpose to a dedicated method
don't show a warning if internet connection is disabled on purpose
update comment
make method names camelCase
use false instead of 0
fix method naming
Merge pull request #3454 from owncloud/fix_hasInternetConnection

isinternetconnectionworking should return false if OC_Config::getValue("has_internet_connection") is false