Adapt var_dump test new php versions.

Newer versions of PHP in 5.4 and 5.5 line add micro seconds
precision to datetime representations.
This adds a regular expression to ignore the .000000 suffix.
Adapt unwind tests for PHP 5.6 style error messages

PHP 5.6 has more detailed error messages, i.e. it says
"on null" instead of "on a non-object".  Replaced this
particular part by a %s match to match both possibilities
so the test suite passes on PHP 5.6 as well as older
versions.
Merge pull request #110 from stesie/fix-tests-php-5.6.0

Fix tests for php 5.6.0