fix php.sh to support double quotes

The current script loses double quotes, meaning this will fail:

    $ ./php.sh -r 'var_dump("hello");'

I was not sure if there was a reason for the `-c` subshell. Hence the PR. If that needs to stay, an alternate fix would be:

    PARAMS="${PARAMS} \"${PARAM//\"/\\\"}\""

(from [here](http://stackoverflow.com/questions/1668649/how-to-keep-quotes-in-args), lol bash)