PHP: ensure 5.3 compatibility, refactor timezone utilities

Relates to #250

Modifications
 - supported version
   - bump required version from 5.1.0 to 5.3.x
   - update README
   - add PHP 5.3 to Travis environments
 - rewrite array declarations: explicitely use array() instead of []
 - move checkPHPVersion to application/Utils.php
 - move timezone functions to application/TimeZone.php
   - cleanup code
   - improve test coverage

Signed-off-by: VirtualTam <virtualtam@flibidi.net>