Add a missing package-info.java for windowing.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82255231
Maven: turn off trimStackTrace. Before the fix, only top level Exceptions are shown, e.t.c. InvocationTargetException and the root Exception is trimmed. Currently, it shows the full stack trace.

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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82451245
Fix typos in README.md.

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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82529793
Dataflow open-sourcing: Add file explaining contribution rules.

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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82665181