Update README.md

Updated readme to fix #19
Merge pull request #20 from andrewtch/patch-1

Update README.md
Merge pull request #23 from stesie/fix-deprecated-calls

Replace deprecated calls to V8 API by newer equivalents
Merge pull request #22 from stesie/add-test-regression-pr14

Add test for regression pointed out in pull request #14
Merge pull request #17 from stesie/fix-object-creation-leak-master

v8js leaks memory if objects are returned to javascript (fix)
Add tests.
Add constructor call callback and create PHP objects as needed.
Call __construct function, if available.
Throw exception if __construct is not public
Handle non-construct call