Changed column type from 'bool' to 'boolean'.

This was most probably just a spelling error from @ad9b1948, but it made
Rails unable to create a proper schema file, leading to me being unable
to prepare a test database from it.

This is a correction to an already existing migration, which means that
all developers would have to reset their database by running 'rake
db:migrate:reset' and presumably reseeding it with 'rake db:seed'.
Niftier summation of total order price.

By utilizing built in methods in Ruby and the Rails framework itself,
one can sum the price of an order in a way that is in my opinion
sweeter, neater and more mind-boggling. Also, it reduces the line count
by a total of 6!