move includes to Cmd
do not break if no slug is present (e.g. playing with play/compile.rb)
set TRAVIS_CMD explicitely, stop using the DEBUG trap
Adds travis_time tags to logs

In order to measure commands' time, variables with
timestamps are set before and after command execution.
Time difference is printed as travis tag `travis_time:finish:`
which can be used to show execution time on travis-web.
use date +%s+N on linux, use gdate +%s+%N if available on darwin, use fall back to second precision otherwise
add a slug to play/compile
remove extra ansi codes for now
rebase to sf-remove_travis_cmd_trap
add a log inspect script
echo within travis_time start/finish
re-add ansi line clearing after carriage return
use echo -e for the final retry failure message, too
reduce noise, prefer raw over cmd for raw commands
refactor to use a travis_cmd bash function to improve the build script readability
it's $output, not $echo
and it is $timing, not $time
use `hash` instead of `which`
uname is Darwin, not darwin
add an extra newline in front of the "Setting up env vars from ..." announcement
silence hash error message