Remove lf.eval.Registry from lf.Global instance.

Having Registry in lf.Global caused issues when trying to inject lf.Global
through constructors, for no good reason. The code-churn required to keep it in
lf.Global is not justified currently, so adding an
lf.eval.Registry.getInstance() seems reasonable.

This eliminates lf.Global dependency from ValuePredicate and JoinPredicate.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=80870605