approvals: Fix case when updates were incorrectly auto-approved

Rewrite and fix condition that decides, whether auto-approval is used.

Previously it unfortunatelly allowed case when updates were auto-approved, even though manual confirmation was required.

Relevant snippet from README regarding the approve logic:

auto_approve_time() and set_auto_approve_time(approve_time) are getter and setter for updater.autorun.auto_approve_time. This is number of hours before approval is automatically granted. This implements update delay.

auto_approve_window() and set_auto_approve_window(window) is getter and setter for updater.autorun.auto_approve_start and updater.autorun.auto_approve_end. They serve to define the window when updates are automatically approved. There can be multiple starts and ends set (it can be a list in UCI). The values them self are crontab like period specifier. If window is defined toggether with auto_approve_time then that time has to elapse before auto approve window is considered.

Closes: #32 (closed)