Fix swig module naming and include path

Hi,
Not sure if the Python bindings are still being worked on, but his gets the SWIG module to build on Mac 10.9.

Original errors encountered:
  * "Cannot find source file: python/pdal.i"
  *  Headers for pdal not found

Not tested beyond `import pdal` and:

```
>>> from pdal import *
>>> dir()
['Bounds_double', 'Bounds_double_swigregister', 
'Range_double', 'Range_double_swigregister', 
'Vector_double', 'Vector_double_swigregister', 
'__builtins__', '__doc__', '__name__', '__package__', 'sys']
```