Skipping testcases that are failing because of other bugs in YSmart.

For more info see the following issues:
See #3: http://github.com/meisam/YSmart/issues/issue/3
See #10: http://github.com/meisam/YSmart/issues/issue/10
See #11: http://github.com/meisam/YSmart/issues/issue/11
Generating the query plan tree and the parse tree in a visual form

This commit lets YSmart generate the query plan and the parse tree in
Graphviz format. The generated output can easily be converted to jpg (or
any other desired format).

See #9: http://github.com/meisam/YSmart/issues/issue/9
Ignoring generated Graphviz output files

OPEN - task 9: Generate the query plan tree in a visual form 
See #9: http://github.com/meisam/YSmart/issues/issue/9