added CUBIRD DB Schema class
finalizing cubrid Schema
CUBRID Query builder
CUBRID added exception about wrong implementation of quoteValue
moved Command::getPdoType() to Schema

this allows different implementation in different DBMS

CUBRID does not supprt PDO::TYPE_BOOL, so we use STRING here which will
be casted by the DBMS
better use int for boolean representation

bit has special syntax for storing and retreiving so we'd need a
converter for that.
Storing 1 bit will result in one byte left padded on the disc so the
result of a query for boolean 0 will be 0x00 and for boolean 1 will be
0x80.
Workaround for broken PDO::quote() in CUBRID 9.1.0

http://jira.cubrid.org/browse/APIS-658
added SchemaTest
Add support for composite FK to cubrid
removed comments
Merge pull request #847 from yiisoft/cubrid

[WIP] Cubrid db support
Added info about custom validator method signature to Model::rules phpdoc