Revert "Test with more PHP versions"

This reverts commit 77bae90847e0c048567e82833e145ece06f7a7c9.
Revert "Use intermediate variable to work in PHP 5.3"

This reverts commit 6fafa642f580801b83c36114826179e590844a5c.
Adjust PHP requirement

The PHP 5.3 lacks some JSON support which we use.

Signed-off-by: Michal Čihař <michal@cihar.com>