1.2.4
* PPI-1357 add heartbeat track events to constants * PPI-1357 add heartbeat functions * PPI-1357 export heartbeat functions as a module * PPI-1357 Move heartbeat functions to clientConfiguration.service * PPI-1357 Move heartbeat to dedicated module * Update modules docs (#26) * Add missing functions descriptions via JSDoc * Regenerate README.md * Fix descriptions formatting