Show how to put libclang.dylib on library path for Mavericks.

Documentation fix for https://github.com/springmeyer/shapely.js/issues/2. After this, npm tests run and pass:

```
$ npm test

Show how to put libclang.dylib on library path for Mavericks.¬
> shapely@0.0.1 test /Users/sean/code/shapely.js
> mocha -gc -R spec



  Error Handling
    ✓ should handle errors correctly

  Geometry API
    ✓ create a Point
    ✓ buffer a Point

  Geometry Cleanup
    ✓ should free geometry ptr inside a Geometry

  Line Interpolation
    ✓ should return point along line

  Geometry Predicates
    ✓ Intersects

  WKB
    ✓ should read a point
    ✓ should read a line

  WKT
    ✓ should read a point
    ✓ should read a line


  10 passing (16ms)
```