Catching invalid nullable columns at parse time.

Modifying SPAC to catch cases where number, integer and boolean columns
are marked as nullable in the database schema.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76743411
Fixing comparison of floating point numbers causing test failures.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76744670
Add missing demos/ folder
Create initial MOE DB.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76748770