improved map annotation add/remove logic with hash map
Merge branch 'master' of https://github.com/sozialhelden/wheelmap-iphone2
Revert "improved map annotation add/remove logic with hash map"

This reverts commit 5fd5d7c635d16977eb9f12c0a6ea21d5a3b49744.
location manager is properly off after the app goes in background.