Improve schedule layout

[karthikb351]

Reported here: https://twitter.com/anandology/status/887978805507346432

@anandology: the time scale on the schedule page is very confusing. 10 mins is 3x longer than 35 mins.

Related: hasgeek/android#3

Possible solution

Calculate the greatest common factor between all the session and break durations, use that as the time for each rowspan, then assign every session item a multiple of the rowspan.

Best case: you have all the sessions and break equally spaced out (so GCM is the same as the duration) so it'll become a simple table with no item needing a rowspan of more than 1.

Worst case: you have 11 hours (9am to 7pm) all 5 minutes apart - which is Funnel admin's granularity. Which gives you a GCM of 5, so 132 rows in the table and items with varying rowspans.