Initial implementation of automatic logging

The fatal flaw is the representation of CCDData arguments. This commit should be backed out and redone if we come up with a good way of handling this.
Remove metadata logging from cosmicray_median because it is not intended to be used separately from cosmicray_clean
Partial implementation of array argument formatting
Use class name as stand-in for array value in out-logging
Use lowercase name internally in the CaseInsensitiveOrderedDict

This makes the names of functions match the python-style lower case instead of FITS-style upper.
Allow to_hdu to convert auto logged metadata to FITS pseudo-compliant header entries

Pseudo-compliance means it breaks no more than one FITS rule...in this case it guarantees that the keyword is 8 characters or less, allowing the CONTINUE convention to be used. If the keyword is longer than 8, HIERARCH must also be used and the two do not work together.
Fixes for python2.6 and 3.x
More format fixes
Fix bug introduced in last commit
Another python 3.x fix
Merge pull request #89 from mwcraig/logging-superpowers

Add auto-logging to ccdproc