enable v8plus_call to be used in any thread

          --- old/./package.json
          +++ new/./package.json
   1    1  {
   2    2          "author": "Keith M Wesolowski <keith.wesolowski@joyent.com>",
   3    3          "name": "v8plus",
   4    4          "description": "utility environment for writing addons in C",
   5      -        "version": "0.0.5",
        5 +        "version": "0.0.6",
        6 +        "contributors": [
        7 +                "Joshua M. Clulow <jmc@joyent.com>"
        8 +        ],
   6    9          "repository": {
   7   10                  "type": "git",
   8   11                  "url": "git://github.com/wesolows/v8plus.git"
   9   12          },
  10   13          "bugs": {
  11   14                  "url" : "http://github.com/wesolows/v8plus/issues"
  12   15          },
  13   16          "dependencies": {
  14   17                  "posix-getopt": "~0.0.1"
  15   18          },
  16   19          "main": "origin.js"
  17   20  }
    

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