Remove the rethrow on failure behavior from all the threaded service implementations.

guava-discuss thread: https://groups.google.com/d/msg/guava-discuss/k_69XGQFPuk/jqTwIRlyP0wJ
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=79991294
Add a constructor to VerifyException to permit a cause to provided alongside a message.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=80128106
Remove references to AsyncLoadingCache from CacheBuilder docs.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=80227076
Remove unnecessary null checks.

Guava pull request #1892
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=80232609
Fix shutdown issue in AbstractScheduledService.

The issue is that if stopAsync() was called after an interation had been
executed (but before it had actually run) then we would fail to unlock
our lock and then shutdown would hang forever.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=80236732