changed ruby to 1.9.3 due to error

ruby: symbol lookup error:
/app/vendor/bundle/ruby/2.0.0/gems/eventmachine-1.0.0/lib/rubyeventmachi
ne.so: undefined symbol: rb_enable_interrupt
2013-08-03T20:23:49.575148+00:00 heroku[web.1]: State changed from
starting to up
2013-08-03T20:23:50.929654+00:00 heroku[web.1]: Process exited with
status 127
2013-08-03T20:23:50.945212+00:00 heroku[web.1]: State changed from up
to crashed