Update PostgreSqlPlatform.php

Decimal column Update if precision or scale was changed
Implement ExceptionConverterDriver for drizzle_pdo_mysql
Updated to use switch case.
Addd missing break
added test to change decimal precision in pgsql
fixed missing uses
fixed test changedproperties
fixed channdged properties
improve driver exception code conversion
add missing MySQL exception for travis
add links to driver exception code reference
fix oci8 TNS connect descriptor
add pdo_oracle driver connection pool option
mention Oracle connection pooling option in docs
fix dropping primary key with autoincrement column in MySQL
fix test groups
add sslmode connection option to pdo_pgsql driver
add missing assertions
Merge pull request #446 from deeky666/DBAL-702

[DBAL-702] Add sslmode connection option to pdo_pgsql driver
Merge pull request #430 from deeky666/DBAL-464

[DBAL-464] Fix dropping primary key with autoincrement column in MySQL