options: reload tab-based: select max. random time

[GoogleCodeExporter]

a) i want to keep reloading a tab even if i changed the page meanwhile. so, 
maybe add an option which disables 
http://code.google.com/p/chrome-reload/source/browse/trunk/src/background.html#6
7

b) 30 min random time is too much for me. so, maybe add an option to use the 
custom value as max

Original issue reported on code.google.com by convincedd on 12 Mar 2012 at 5:49