fixed hourly roll period's initial filename
fixed hourly roll period's initial filename

Summary:
When rotate_period=hourly and no logs exist for a given category,
the log's filename is created incorrectly. The filename suffix is 0,
when it should be the current hour.

btnguyen2k/scribe,haozi3156666/scribe,Ayear0608/scribe,Tony-Zhang03/scribe,odin1314/scribe,facebookarchive/scribe,uuunic/scribe,yshaojie/scribe,Ayear0608/scribe,rdio/scribe-public,iyagi15/scribe,iyagi15/scribe,uuunic/scribe,yshaojie/scribe,yshaojie/scribe,fengshao0907/scribe,tempbottle/scribe,uuunic/scribe,odin1314/scribe,tempbottle/scribe,haozi3156666/scribe,uuunic/scribe,haozi3156666/scribe,btnguyen2k/scribe,iyagi15/scribe,facebookarchive/scribe,abhishekdelta/scribe,iyagi15/scribe,tempbottle/scribe,facebookarchive/scribe,btnguyen2k/scribe,lawrencewu/scribe,Tony-Zhang03/scribe,esteigler/scribe,abhishekdelta/scribe,rdio/scribe-public,yshaojie/scribe,swiftype/scribe,rjbhewei/scribe,tempbottle/scribe,schmits/scribe,fengshao0907/scribe,rjbhewei/scribe,lawrencewu/scribe,rjbhewei/scribe,tempbottle/scribe,esteigler/scribe,schmits/scribe,swiftype/scribe,Tony-Zhang03/scribe,Ayear0608/scribe,kangkot/scribe,schmits/scribe,rdio/scribe-public,btnguyen2k/scribe,facebookarchive/scribe,Ayear0608/scribe,facebookarchive/scribe,uuunic/scribe,apprentice1989/scribe,btnguyen2k/scribe,Tony-Zhang03/scribe,esteigler/scribe,kangkot/scribe,kangkot/scribe,apprentice1989/scribe,apprentice1989/scribe,odin1314/scribe,fengshao0907/scribe,schmits/scribe,swiftype/scribe,haozi3156666/scribe,odin1314/scribe,rjbhewei/scribe,odin1314/scribe,kangkot/scribe,esteigler/scribe,schmits/scribe,apprentice1989/scribe,fengshao0907/scribe,lawrencewu/scribe,abhishekdelta/scribe,lawrencewu/scribe,yshaojie/scribe,abhishekdelta/scribe,haozi3156666/scribe,Tony-Zhang03/scribe,rjbhewei/scribe,rdio/scribe-public,Ayear0608/scribe,lawrencewu/scribe,abhishekdelta/scribe,fengshao0907/scribe,apprentice1989/scribe,esteigler/scribe,kangkot/scribe,iyagi15/scribe,rdio/scribe-public,swiftype/scribe,swiftype/scribe