[2.0] DDC-84 - Added increment alter table / update schema tests for Oracle Platform - Fixed a simple bug in Postgres Tests.

[2.0] DDC-84 - Added increment alter table / update schema tests for Postgres Platform - Fixed several bugs in Doctrine\DBAL\Platforms\PostgreSqlPlatform

[2.0] Fixed DDC-101, DDC-102 - Ensure defaults for string length and field nullability are handled consistently in both update and create schema commands of SchemaTool.

[2.0] DDC-84 - Add Mysql Platform unittests for incremental changes of the metadata for the schematool update function. Fixed some quirks in the Unit-Test suite alongside, Fixed changes of length in SchemaTool update.