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
add PHP 5.6 to .travis.yml
Merge pull request #111 from sasezaki/patch-1

add PHP 5.6 to .travis.yml
v8 compliation requires gclient

http://dev.chromium.org/developers/how-tos/install-depot-tools
Merge pull request #112 from sameoldmadness/install-depot_tools

v8 compliation requires gclient
Merge branch 'cscott/issue-64' (ctx_lifecycle test).

Test adapted to current behaviour of V8Js, that the situation is
properly handled, but not by keeping objects valid, but by
invalidating all of them.