Bump src/smoke-tests and allow to skip smoke tests

- via bosh manifest, you can choose to skip some tests

Bump :
  Joseph Rodriguez:
     Increase timeout for cf logs --recent test
     Temporarily disable non-deterministic syslog drain tests so the cf-runtime pipeline is not artificially broken
  Eric Malm and Luan Santos:
     Add more explanation about what smoke tests are and when to run them