Added boolean type for method describeColumns, code cleanup for adapaters at this method.
Added constraint creation for foreign key
Unit test corrected to check CONSTRAINT, sqlite adapter has been corrected
Tabs and memory leak fixes.
Merge pull request #1562 from lantian/1.2.5

PDO/Adapter: decribeColumns method fixes.
Merge remote-tracking branch 'upstream/1.2.5' into 1.2.5