Loading cron schedule and registering cron after `init` action

At this moment both WP and plugin are initialized so it can now access
plugin data if required
Allow to change cron interval using a filter

Fixes #195
Merge branch 'master' into cron-interval

Conflicts:
	supportflow.php
Merge pull request #205 from VarunAgw/cron-interval

Filter the cron interval so it can be easily customized.