Correcting test for Config.class.php

The constant used to load config file i.e CONFIG_FILE was config.inc.php while it did not exist in code base, which was causing two similar test-case with no config-file.
CONFIG_FILE has been replaced with "config.sample.inc.php" which can be tested for.
 
Signed-off-by: A V Minhaz <minhazav@gmail.com>
Update PMA_Config_test.php

As per discussion in mailing list, another object is used to check for file permission while global object remains same!
Signed-off-by: A V Minhaz <minhazav@gmail.com>
testing permission for test object

Signed-off-by: A V Minhaz <minhazav@gmail.com>
Test case for Config.class.php fixed

Testcases modified:
Two test cases - one for no config file , other with config file

Signed-off-by: A V Minhaz <minhazav@gmail.com>
Merge pull request #994 from mebjas/QA_4_1

Correcting test for Config.class.php