inttest/rgen_1: double the timeout a second time

60s still seems to be too low, as it timed out for at least the R15B01
job of the timeout patch merge:
https://travis-ci.org/rebar/rebar/builds/15051701
https://travis-ci.org/rebar/rebar/jobs/15051703
Clean up rebar.config.script
Merge pull request #198 from tuncer/clean-up-rebar-config-script

Clean up rebar.config.script
Merge pull request #190 from tuncer/quadruple-timeout

inttest/rgen_1: double the timeout a second time