Fixed #1272938: added new permission 'access own pay-per-node balance'. Only users that have this permission can see Pay per node tab on own page profile.

Removed unnecessary code
Fixed bugs due to upgrade from D6 (API changes, blocks and permissions).
Renamed some functions to avoid conflicts with D7 hooks (checked with Coder).
Fixed bug on paypernode_get_types: this function does not filter correctly allowed node types in pay per node system.

Fixed problem with default values of radio buttons on admin form for bulk assignment.
Fixed bug on pay per node administration overview page (no results displayed).

Fixed bug #759826 by Alexander N: fixed amount of nodes an user can create upon order completion using Ubercart integration.