add support for sqlite3

some code copied from
http://sourceforge.net/p/symmetricds/code/7054/tree/tags/symmetric-build-2.5.13/symmetric-ddl/src/
fix sqlite3 foreign key support

SQLite3 supports embeded and nameless foreign key only.
and Not supports edit constraint after creating table.
Merge pull request #1 from tohosaku/develop

Develop