Update GitHubResolver.js

was seeing "error path must be a string", using console _tempDir was an an array of [string, object] so I reset the _tempDir to have the correct value

fullstack:
bower requirejs#~2.1.14                        error path must be a string

Stack trace:
TypeError: path must be a string
    at Object.fs.unlink (fs.js:760:11)
    at rimraf_ (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\rimraf\rimraf.js:88:11)
    at rimraf (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\rimraf\rimraf.js:44:3)
    at Promise.apply (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\q\q.js:1078:26)
    at Promise.promise.promiseDispatch (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\q\q.js:741:41)
    at C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\q\q.js:1304:14
    at flush (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\q\q.js:108:17)
    at process._tickCallback (node.js:419:13)

Console trace:
Trace
    at StandardRenderer.error (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\lib\renderers\StandardRenderer.js:72:17)
    at Logger.<anonymous> (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\bin\bower:111:22)
    at Logger.emit (events.js:95:17)
    at Logger.emit (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\bower-logger\lib\Logger.js:29:39)
    at C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\lib\commands\index.js:40:20
    at _rejected (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\q\q.js:797:24)
    at C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\q\q.js:823:30
    at Promise.when (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\q\q.js:1035:31)
    at Promise.promise.promiseDispatch (C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\q\q.js:741:41)
    at C:\Users\bneil\AppData\Roaming\npm\node_modules\bower\node_modules\q\q.js:557:44

System info:
Bower version: 1.3.7
Node version: 0.10.29
OS: Windows_NT 6.1.7601 x64