A version that can be merged with master
Makefile version of expandable framework.
Also, shrinking in aggregations' open is accelerated.
some wierd bugs waiting to solve.
PerformanceInfo now has a scalability vector, which provides guidance
the on-demand scheduler.
Scheduler directory is removed, and the makefiles are updated
accordingly.
the code for tpc test is updated to the new version, in response to the
modificatoins to getAttribute() function.
data generate now can partially support assigning data distributions.
Merge branch 'ExpandableFramework'

Conflicts:
	BlockStreamIterator/ParallelBlockStreamIterator/BlockStreamProjectIterator.cpp
	BlockStreamIterator/Serialization/RegisterDerivedClass.cpp
	Parsetree/semantic_analysis.cpp
	README.md
	Server.cpp
	Test/TestMain.cpp
	common/ExpressionItem.cpp
	common/data_type.h
	common/types/Test/data_type_test.h
	conf/config