Added unit and integration tests for:

1. Logs:
   • Tested mkTimestampFormatter formatting and shortenCaller path trimming.
2. Resolve:
   • Added newLogSrc tests with plain text file, with gzipped file, with window opt and with empty file checks
   • Added resolveSource test with a valid source
   • Added PipeStdin test.
   • All with verified timestamp detection
3. Rules:
   • Added unit test for shouldUpdateExe and shouldUpdateRules with various semantic versions.
   • Added test for postUrl using httptest.
4. Sigs:
   • Added test for HandleKill cancel signals

Please let me know if there are some feedbacks! Thanks!
Partially closes #48
cc @tonymeehan