remove date.timezone setting for hhvm

using ...

before_script:
  - echo 'date.timezone = "America/Chicago"' >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini

... fails with:

Using worker: worker-linux-2-1.bb.travis-ci.org:travis-linux-18
git.1
$ git clone --depth=50 --branch=develop-2 git://github.com/auraphp/Aura.Web.git auraphp/Aura.Web
Cloning into 'auraphp/Aura.Web'...
remote: Counting objects: 1293, done.
remote: Compressing objects: 100% (606/606), done.
remote: Total 1293 (delta 624), reused 1243 (delta 588)
Receiving objects: 100% (1293/1293), 288.44 KiB, done.
Resolving deltas: 100% (624/624), done.
$ cd auraphp/Aura.Web
git.3
$ git checkout -qf c2833481f2dc34e60d32a4b1e3669fa882db1318
$ phpenv global hhvm
$ php --version
HipHop VM v2.3.0 (rel)
Compiler: heads/HHVM-2.3-0-ga12fa4ac4dacbb45348a6ff2b3775f895883f934
Repo schema: 30349d0b2f68667d4e5a3fd291f2274c608f9e29
$ composer --version
Cannot open log file: /var/log/hhvm/error.log
HipHop Strict Warning: It is not safe to rely on the system's timezone settings. Please use the date.timezone setting, the TZ environment variable or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'UTC' for 'UTC/0.0/no DST' instead in phar://composer.phar/bin/../src/../src/Composer/Console/Application.php on line 65
Composer version 80499bb02418711b34bba59c1a6d8032429e5702 2013-12-06 12:32:19
$ echo 'date.timezone = "America/Chicago"' >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
/home/travis/build.sh: line 150: /home/travis/.phpenv/versions/hhvm/etc/php.ini: No such file or directory
The command "echo 'date.timezone = "America/Chicago"' >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini" failed and exited with 1 during before_script.
Your build has been stopped.