Added base n decode function.  Added base36encode and base36decode
convenience functions.
Added optional pad_length parameter to base36encode.
Added test data for naming.
Implemented new object name generation method according to #132. 
Getting and incrementing the counter stored in VOSpace is not yet 
implemented.
Moved encoding and decoding functions into a separate coding module.
Implemented methods for reading and incrementing the object counter
for an epoch/field.
Switched controller over to use new method for object name generation.
Added dry run name generator which doesn't update VOSpace counters.
Added --dry-run option to validate.py, in which case no modifications will
be made to VOSpace.  Currently it will only work on local input directories,
providing an error message to the user if they attempt to use it in VOSpace.
The application will now abort if the output directory is not local.
Removed old name source method and unused encode shortcuts.
Merge pull request #137 from drusk/object_naming

Closes #132.