Tidy some tests

- Added `StoreFactory::setDefaultStoreForUnitTest` to set a mock instance during testing
- ConceptParserFunctionTest extends \PHPUnit_Framework_TestCase
- SemanticDataTest extends \PHPUnit_Framework_TestCase
- SimpleQueryResultQueryProcessorIntegrationTest extends \PHPUnit_Framework_TestCase
- StoreFactoryTest
- AskArgsTest
- BrowseBySubjectTest
- InfoTest

### Fuseki-run
- Before: Tests: 2031, Assertions: 6018, Failures: 4, Skipped: 75
- After : Tests: 2030, Assertions: 6051, Failures: 4, Skipped: 54.

Relates to #337, #339