added test for $bitsAllClear

[vic-tsang]

This PR added tests for bitsAllClear with the following categories:

• test_bitsAllClear_: test that specifically targets $bitsAllClear
• test_bitwise_common.py: tests which targets all bitwise operators ($bitsAllClear, $bitsAllSet, $bitsAnyClear, $bitsAnySet) which outputs the same results (e.g. common invalid input errors, and tests that silently skips the evaluation)
• test_query_combination_bitwise_operators.py: a sample of tests with mixed operators

Ref: Issue #30

PR depends on #73