implement ThriftSuperStructuredDataSupport

EBD-10713
Introduced abstract superclass for thrift structured data support for
shared code between columns and supercolumns
Add javadoc comment

EBD-10713
Added system test for super column families

EBD-10713
Bumped version number to 2.4.0
fixed some bugs in super column family support
Added abstract class for thrift system tests
Merge pull request #29 from ebuddy/EBD-10713_supercolumn-family-dao

Ebd 10713 supercolumn family dao