Working Reference Interpreter.  Remove fake files.  Updates to common as reference interpreter clarified things.
Merge branch 'prototype' into executor-java

Conflicts:
	sandbox/prototype/common/src/main/java/org/apache/drill/common/expression/ValidationError.java
	sandbox/prototype/common/src/main/java/org/apache/drill/common/expression/types/DataTypeFactory.java
	sandbox/prototype/common/src/main/java/org/apache/drill/common/expression/visitors/GetIdentifiers.java
	sandbox/prototype/common/src/main/java/org/apache/drill/common/logical/data/Scan.java
	sandbox/prototype/common/src/main/java/org/apache/drill/common/physical/schema/SchemaIdGenerator.java
Move closer to RecordIterator interface