[server][ItemTablePtr] Remove unused method innerJoin
[server][ItemTablePtr] Remove unused method leftOuterJoin
[server][ItemTablePtr] Remove unused method rightOuterJoin
[server][ItemTablePtr] Remove unused method fullOuterJoin
[server][ItemTablePtr] Remove unused method crossJoin
Merge pull request #434 from project-hatohol/item-table-ptr-remove-unused-methods

[server][ItemTablePtr] Remove unused methods