[BACKLOG-256]   Adding Flexjson serialization/deserialization of DatabaseType/DatabaseTypesList to handle the defaultOptions Map.  This follows the same approach used for DatabaseConnection/DatabaseConnectionList.
Correct serialization of the options Map is required to set a default options value in the connection dialog.
[BACKLOG-256]  Adding xul overlay for kettlethin, which omits the database name textbox (since it uses the fixed value 'kettle').
[BACKLOG-256]  Corrected class used in deserialization of DatabaseType.
Merge pull request #455 from mkambol/backlog-256

[BACKLOG-256]   Adding Flexjson serialization/deserialization of Databas...