added CUBIRD DB Schema class
finalizing cubrid Schema
CUBRID Query builder
CUBRID added exception about wrong implementation of quoteValue
cubrid unit tests WIP
avoid hanging test on bindValue problems (close db connection in tearDown)
added CURBID to the docs
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.
custom bindValue test for cubrid
Workaround for broken PDO::quote() in CUBRID 9.1.0

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

[WIP] Cubrid db support