Merge pull request #29 from ne0h12/master

Fixed zendframework repositories in composer.json

- Addressed issue #18 where arrays may potentially allow for compromi…

…sing the sandbox by encapsulating unsandboxed callables

- changed the way values are passed as arguments to calls to address …

…referencing issues

- Fixed bug with prepare_vars()

- Updated documentation

- Fixed define_namespaces bug

- Fixed out of place comment, tweaked tests