Add Integration Test with db:dump --strip

[ktomk]

In #199 a miss on actual dump execs came to light. Write one test that creates a dump.sql file that should reflect both stages, that is the table creation only and the table creation and data part (two different mysql commands of which appends to the dumpfile of the first one).

With a blank install on Travis this test should run fast enough. Test could be done for the created file's size with a certain weight.

[ktomk]

Test of dump-file by the file-size now in develop:

• N98\Magento\Command\Database\DumpCommandTest::realDump