re-arrange adapter methods (a bit logically) + hide private methods
some jdbc_ methods only needed for AR < 3.0
substitute_binds and extract_sql is private API
mysql - no need to re-invent substitute_binds in exec_insert
all modify_types impls should honor super
[oracle] avoid CREATE DDL failure when BLOB has length specified
+ an explicit column class for Oracle; prepare for TIMESTAMP support
perform some code cleanup
[oracle] fix broken `string_to_time` due previous changes; explain support
also since Oracle supports TIMESTAMP for quite a while we should not create DATE columns for a :timestamp column type
guard against regression (#192) + fix tests green due modify_types super
[postgres] ignore binary precision / limit for bytea
borrowing binary tests from Rails to guard against regressions e.g. #174
run the binary tests with MySQL/Derby/H2 and HSQLDB as well