Fix availability calculation for hourly stats

The bug happens when a check is just started or paused

Refs #197
Newline in the end of file
Change calcul of availability & downtime for hour & day to take paused time & tested time into account
Fix errors on uptime bar : color & duration
Fix errors on uptimeBar
Fix error when a check as a long period of pause
Remove condition on current interval in uptimeBar
Merge pull request #200 from fzaninotto/availability_fix

[RFC] Fix availability calculation