add USE_EXACT_ALARM to be granted on install.

[wilsonrc]

ISSUE-474 Add USE_EXACT_ALARM permission. Is new permission that is only to be used by Calendar or alarm clock apps

According to documentation: The USE_EXACT_ALARM permission will be granted on installation, and apps holding this permission will be able to schedule exact alarms just like apps with the SCHEDULE_EXACT_ALARM permission.

[tibbi]

ok thanks