Specify RACK_ENV=production in .bash_profile

Otherwise, when you run `bundle exec foreman start`, you would get:

20:01:43 web.1     | rake aborted!
20:01:43 web.1     | SQLite3::SQLException: no such table: delayed_jobs: UPDATE 
"delayed_jobs" SET "locked_by" = NULL, "locked_at" = NULL WHERE "delayed_jobs"."
locked_by" = 'host:us1 pid:5179'

...indicating that we are not in production env, and it is using the sqlite database.
Merge pull request #184 from jiehanzheng/patch-1

Specify RACK_ENV=production in .bash_profile