Added new sub-package, utils. Added modules, json.py and templatefile.py

Added
=====

* New module wmt.utils.json to hold utilities for working with JSON
  files. In the future, will move stuff from wmt.cca.json to here.
* New module wmt.utils.templatefile defines the TemplateFile
  class.
Changed hydrotrend template file to use new key strings.
Added new command wmt_fill what fills template files.
Removed usused modules.

Removed
=======

* Removed wmt.cca.templates and moved most of the functionality to
  wmt.utils.templatefile.
* Removed unused urls.py