serialize test for derby, h2 and hsqldb (their low on tests thus won't hurt)
run serialize tests with DB2 (this is mainly why we backported those tests)

this got us into pretty good compatibility "only" 2 (serialize) failures on 3.2 :
- test_serialize_with_coder(DB2SerializeTest)
- test_serialize_with_bcrypt_coder(DB2SerializeTest)

rearranged some adapter methods a bit to require less "logical" src jumps

extract column value extraction + dump logic into a helper to be shared with others that handle lobs in a after_save callback
[oracle] (shared) serialized attribute support + tests for oracle
[mssql] [firebird] [informix] (shared) serialized attribute support
[sqlite3] execute on insert_sql + savepoint support
make sure delete without WHERE clause is tested
move (mysql & postgres) quoted values caching into the adapter class
avoid private API substitute_binds and extract_sql
besides on derby make sure we never modify the passed sql param
use a class variable for tracking whether lob callbacks where added
(avoid ruby warnings with instance vars)
re-invent execute to "log" (sql) name correctly based on AR version
avoid substitute_binds completely and backport to_sql for everybody