move logic to know if a project is using pagarme to project model
adjust project_unsuccessful notification to handle with projects using pagarme
adjust text on waiting_funds project notification for projects that using pagarme
adjust text on contribution project unsuccessful notification
adjust credits warning on new contribution
user can see credits warning when project is not using pagarme
added link to blog post that describe the credits changes
Merge pull request #947 from devton/die-credits/notifications-changes

change some notifications to explain about the end of credits