suppress model_class field in json output.
format json according to data type. also fix a bug that it only escape " in string.

null, true, and false are respected.
escape string according to json.org.
Date/Timestamp object is converted to iso8601 UTC format.
cleanup.
Fixes schema issue(#182)

Moving away from system prop to get the schema name.
usage: if schema is used you'll have to use @Table annotation
instead of @Table("tablename") use @Table("schemaname.tablename)
do not treat db as inited, if exception happened during Registry.init()
initialize MetaModels.many2ManyAssociations in MetaModels.addMetaModel() when it is called from synchronized Registry.init(), not in MetaModels.getEdges(), otherwise null pointers and concurrent modifications when there is high concurrency
use immutable list used for cache
all scripts are executable
upgraded to new MSSQl driver