Fixed up package installer for OSX

Main issue was building a version of Ruby for the path /usr/local/turbot
as opposed to /usr/local/heroku

Needed to take these steps to build

```
git clone https://github.com/ddollar/ruby-osx-packager
cd ruby-osx-packager/vendor/ruby-build
PREFIX=/Users/xavierriley/openc/ruby-osx-packager/vendor/ruby-build/
./install.sh
cd ../../
CC=/usr/local/bin/gcc-4.6 rake
```

The last bit is because it needs gcc to compile Ruby as opposed to
clang. This version of Ruby is hosted at
https://s3.amazonaws.com/static.xavierriley.co.uk/ruby-1.9.3-p194.pkg
for now.

The rest of these changes were to pull in files that are required for
turbot. To build a pkg for distribution, make sure you have all gems
installed with

```
bundle install
```

then run

```
rake pkg:build
```