updated convert function  to include uppercased values

fixed parameter order in conditions

Changes after Ocramius comments

fixed bug when $item was set as bool true value
added 'off' literal

added postgresql literals to Boolean conversion

If you have a role "postgres" in PostgreSQL that is described like this:
```
-- Role: postgres
CREATE ROLE postgres LOGIN
  ENCRYPTED PASSWORD 'md53175bce1d3201d16594cebf9d7eb3f9d'
  SUPERUSER INHERIT CREATEDB CREATEROLE REPLICATION;
ALTER ROLE postgres IN DATABASE sf_test
  SET search_path = "$user", public, access, geographic, rrhh;
```

At the time when I execute the statement (Part of $schema value in the line 348):
```
SELECT string_to_array((select replace(replace(setting,"$user",user),' ','') from pg_catalog.pg_settings where name = 'search_path'),',')
```
I fetch this result:
```
{public," access"," geographic"," rrhh"}
```
Look the space character that is on the start of each string.This error does not match any namespace to which the role has access. This is critical when you have PostgreSQL database and you work with schemas.

This reverts commit 5a46f577.

[DBAL-555] replace a bunch of occurances of $diff->name and $diff->newName with quoted identifier version.

Put the responsibility to give the default schema name from CreateSchemaSqlCollector to the Platforms (abstract, sqlserver, postgresql)

Decimal column Update if precision or scale was changed

- Fixed docblocks
- Removed return statements on void methods
- Cleaned up unused private / local variables
- Fixed license issues
- Removed SVN leftovers
- Fixed doctrine-project.org links
- Added line breaks before return statements

Add getGuidExpression() to PostgreSqlPlatform so that UUID support
works properly