Add e2e correctness tests

[msm-code]

Create a set of correctness tests, using the current e2etest framework.

1. Use a real-world Yara rule corpus (maybe the same that mquery uses - https://github.com/CERT-Polska/mquery/tree/master/src/tests/yararules/testdata).

2. Store a predefined set of test malware files (for example, 1000) somewhere (left to discussion - probably hosted zip file). There should be at least one matching file for every yara rule (if possible).

Index all the downloaded files, and for every yara rule and set of expected results:

• run ursadb query and ensure there are no false positives
• run yara directly (using https://github.com/VirusTotal/yara-python) on all the files and ensure that there are no false negatives