Added rules endpoints

Added:
GET /projects/project_id/rules
POST /projects/project_id/rules
GET /projects/project_id/rules/rule_id
PUT /projects/project_id/rules/rule_id
DELETE /projects/project_id/rules/rule_id
GET /projects/project_id/rules/rule_id/copy
POST /projects/project_id/rules/rule_id/backfill

Hope this is ok.