Put output in current working directory by default

Fixes the following traceback if the --outdir argument is not provided.

    Traceback (most recent call last):
      File "./run_sky_area.py", line 117, in <module>
        with open(os.path.join(args.outdir, 'skypost.obj'), 'w') as out:
      File
    "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/posixpath.py",
    line 77, in join
        elif path == '' or path.endswith('/'):
    AttributeError: 'NoneType' object has no attribute 'endswith'
Spelling error
Fix error in spelling of method name

Fixes this error:

    Traceback (most recent call last):
      File "./run_sky_area.py", line 141, in <module>
        None, None, None)
      File "./run_sky_area.py", line 48, in save_areas
        areas = skypost.sky_areas(cls)
    AttributeError: 'ClusteredKDEPosterior' object has no attribute
    'sky_areas'
Merge pull request #1 from lpsinger/first_run_fixes

First run fixes