Add minstache support

Add [minstache](https://github.com/visionmedia/minstache) support, as per #57.
```
4) minstache should support locals:
     TypeError: Cannot read property 'name' of undefined
    at eval (<anonymous>:19:33)
    at render (/home/rob/Documents/consolidate.js/node_modules/minstache/index.js:26:10)
    at Function.exports.minstache.render (/home/rob/Documents/consolidate.js/lib/consolidate.js:491:54)
    at /home/rob/Documents/consolidate.js/lib/consolidate.js:146:25
    at /home/rob/Documents/consolidate.js/lib/consolidate.js:99:5
    at fs.js:266:14
    at /home/rob/Documents/consolidate.js/node_modules/mocha/node_modules/glob/node_modules/graceful-fs/graceful-fs.js:103:5
    at Object.oncomplete (fs.js:107:15)
  

  5) minstache should not cache by default:
     TypeError: Cannot read property 'name' of undefined
    at eval (<anonymous>:19:33)
    at render (/home/rob/Documents/consolidate.js/node_modules/minstache/index.js:26:10)
    at Function.exports.minstache.render (/home/rob/Documents/consolidate.js/lib/consolidate.js:491:54)
    at /home/rob/Documents/consolidate.js/lib/consolidate.js:146:25
    at /home/rob/Documents/consolidate.js/lib/consolidate.js:99:5
    at fs.js:266:14
    at /home/rob/Documents/consolidate.js/node_modules/mocha/node_modules/glob/node_modules/graceful-fs/graceful-fs.js:103:5
    at Object.oncomplete (fs.js:107:15)
  

  6) minstache should support caching:
     TypeError: Cannot read property 'name' of undefined
    at eval (<anonymous>:19:33)
    at render (/home/rob/Documents/consolidate.js/node_modules/minstache/index.js:26:10)
    at Function.exports.minstache.render (/home/rob/Documents/consolidate.js/lib/consolidate.js:491:54)
    at /home/rob/Documents/consolidate.js/lib/consolidate.js:146:25
    at /home/rob/Documents/consolidate.js/lib/consolidate.js:99:5
    at fs.js:266:14
    at /home/rob/Documents/consolidate.js/node_modules/mocha/node_modules/glob/node_modules/graceful-fs/graceful-fs.js:103:5
    at Object.oncomplete (fs.js:107:15)
  

  7) minstache should support rendering a string:
     TypeError: Cannot read property 'name' of undefined
    at eval (<anonymous>:19:33)
    at render (/home/rob/Documents/consolidate.js/node_modules/minstache/index.js:26:10)
    at Function.exports.minstache.render (/home/rob/Documents/consolidate.js/lib/consolidate.js:491:54)
    at Context.<anonymous> (/home/rob/Documents/consolidate.js/test/shared/index.js:76:18)
    at Test.Runnable.run (/home/rob/Documents/consolidate.js/node_modules/mocha/lib/runnable.js:204:15)
    at Runner.runTest (/home/rob/Documents/consolidate.js/node_modules/mocha/lib/runner.js:374:10)
    at /home/rob/Documents/consolidate.js/node_modules/mocha/lib/runner.js:452:12
    at next (/home/rob/Documents/consolidate.js/node_modules/mocha/lib/runner.js:299:14)
    at /home/rob/Documents/consolidate.js/node_modules/mocha/lib/runner.js:309:7
    at next (/home/rob/Documents/consolidate.js/node_modules/mocha/lib/runner.js:247:23)
    at Object._onImmediate (/home/rob/Documents/consolidate.js/node_modules/mocha/lib/runner.js:276:5)
    at processImmediate [as _immediateCallback] (timers.js:330:15)
```