Set timezone to UTC as a sane default.

Using EST was not a great default as that only works for a narrow region
of people (literally ;)).  Instead, setting it to UTC at least gives the
global community an expected standard to rely on (and it's what PHP
defaults to when you don't set it).

README.md

@@ -17,6 +17,9 @@ purpose of building PHP composer packages.  It provides several key features:
 * Composer bin directories are automatically included in `PATH`.  Both a
   relative `vendor/bin` directory, and the global `$COMPOSER_HOME/vendor/bin`
   directory are included in the `PATH`.
+* Timezone set to `UTC` by default to remove the warnings with PHP's date and
+  time functions.  This can be overridden by updating
+  `/etc/php/conf.d/timezone.ini`.
 
 ## Usage
 This library is useful with simple `composer.json`'s from the command line.

timezone.ini

@@ -1,2 +1,2 @@
 [Date]
-date.timezone = America/New_York
+date.timezone = UTC