fix include template path
add logging configuration to console in settings.py
changes related create/update pledge
* add PledgeUpdateView
* add PledgeCreateView dispatch method
* add validation of the amount needed to reach threshold in PledgeForm clean method
* substitute "backed" name methods by "reach_threshold" in models and forms
* change success_url by get_success_url in ProposalCreateView
* add unicode method to models
* use thresh logger in getLogger