removed unnecessary  setup/teardown-methods

* removed "charset" patch
* implemeted resource_type compare with in_array instead of regex
* implemented functional tests for connection and statement.

The test is partially skipped due to:

1. Fetching blob as binary string from pdo_sqlsrv requires using `PDOStatement::bindColumn()` and `PDOStatement::fetch(PDO::FETCH_BIND)` which are not supported by the DBAL.
2. Setting encoding on the connection level is not supported: https://msdn.microsoft.com/en-us/library/ff628164(v=sql.105).aspx

[DBAL-2546] Fixed the failure of `Functional\StatementTest::testIncompletelyFetchedStatementDoesNotBlockConnection()` on pdo_mysql + libmysql

The test case being fixed should reset shared connection during teardown as one if its methods modifies connection attributes.

- fixes platform's COMMENT ON statement support
- implements reverse engineering for column comments
- marks boolean column type commented for distinction

fixes #2182

fixes #1339
closes #921

Can't use short array in php < 5.4