Merge branch 'release-0.2.6' into develop
Refactor events so components become clients.
Trying to init events server raises when given port is not free.

* Also fix and improve some tests.
Add doc and tests about events sync/async behaviour.

* Also fix docstrings identation so sphynx doesn't complain.
Merge remote-tracking branch 'drebs/feature/3246-refactor-events-so-components-become-clients' into develop
Add leap_check helper method, #3007 related issue.
Merge remote-tracking branch 'ivan/feature/add-leap-check' into develop
Fix events doc about reqcbk signature. Closes #3261
Merge remote-tracking branch 'drebs/bug/3261-fix-events-doc-about-reqcbk' into develop
Fold in changes
Bump version to 0.2.7
Merge branch 'release-0.2.7'