Fixed bug where the setup script would attempt to trim() a non-string object.

While running the titanium setup script, I got an error complaining about 'trimming' a boolean object. To fix this, I added a toString() call before the trim() call.

Stacktrace:
```
TypeError: Object true has no method 'trim'
    at /usr/local/lib/node_modules/titanium/lib/commands/setup.js:316:42
    at Array.forEach (native)
    at /usr/local/lib/node_modules/titanium/lib/commands/setup.js:315:25
    at /usr/local/lib/node_modules/titanium/node_modules/prompt/lib/prompt.js:316:32
    at /usr/local/lib/node_modules/titanium/node_modules/async/lib/async.js:116:25
    at assembler (/usr/local/lib/node_modules/titanium/node_modules/prompt/lib/prompt.js:313:9)
    at /usr/local/lib/node_modules/titanium/node_modules/prompt/lib/prompt.js:322:32
    at /usr/local/lib/node_modules/titanium/node_modules/prompt/lib/prompt.js:597:5
    at onLine (/usr/local/lib/node_modules/titanium/node_modules/prompt/node_modules/read/lib/read.js:111:5)
```