Evaluate and fix SQLServer Manual tests

SQL Server Manual tests seem to be somewhat abandoned as there are several failing test cases which don't bring any value to the quality of Sqoop. I took a look at them and found some improvement areas besides the failing test cases. Fixing and improving these tests would make easier to execute them in case of SQL Server related changes which would help to keep Sqoop more robust.

The following 14 test classes are affected by this ticket:

• com.cloudera.sqoop.manager
  • SQLServerManagerExportManualTest
  • SQLServerManagerImportManualTest
• org.apache.sqoop.manager.sqlserver
  • SQLServerDatatypeExportDelimitedFileManualTest
  • SQLServerDatatypeExportSequenceFileManualTest
  • SQLServerDatatypeImportDelimitedFileManualTest
  • SQLServerDatatypeImportSequenceFileManualTest
  • SQLServerHiveImportManualTest
  • SQLServerManagerManualTest
  • SQLServerMultiColsManualTest
  • SQLServerMultiMapsManualTest
  • SQLServerParseMethodsManualTest
  • SQLServerQueryManualTest
  • SQLServerSplitByManualTest
  • SQLServerWhereManualTest

Scope of this ticket is only fixing the test cases and also make them unified from the DB connect string and credentials point of view. However, an extensive refactor could be made in these test classes, which is addressed in another ticket, see SQOOP-3170