Merge pull request #63 from Zentific/expose_address_width

Expose address width via the public API
Bugfix - linux/memory.c : linux_pgd_to_pid was attempting to reach task_struct->pid by using pgd_offset (copy-paste bug)
linux/memory.c : Simplify linux_get_taskstruct_addr_from_pid and linux_get_taskstruct_addr_from_pgd, and make sure they return the task_struct address as implied by the function name (previously returned address of the related task_struct->tasks)
Bugfix : linux_get_taskstruct_addr_from_pgd and linux_pid_to_pgd were unable to resolve the pgd if task_struct->mm == NULL in a kthread or during a system call, so be sure to check task_struct->active_mm in those instances