FIX: do not display event too far in the future

This patch add a filter to drop events after the "lookahead" value (in local
time). Add a comment line to clarify why we have to fetch event farther in the
futur for "all day" events.

Change-Id: I8e2282768962682ecbf9f04b242297e67d3f103f
Merge branch 'cm-10.1' of github.com:CyanogenMod/android_packages_apps_LockClock into cm-10.1