Simplify alarm API.

This change removes a corner case that needs to be handled (what happens if you
add an alarm twice?). This corner case was never used, nor tested.
	Change on 2014/12/15 by ctiller <ctiller@google.com>
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82168179
5 files changed