Merge ser tls module into the sip-router repository

Merge ser tls module into the sip-router repository

* commit 'ser/modules/tls': (50 commits)
  - a set of minimalistic config files for testing purposes
  - tls module todo
  - default key and certificate names changed to ser-selfsigned*
  - updated to the latest changes in the cfg parser
  - Use the new configuration file parser
  - fixed includes (rm malloc.h) due to portability problems
  - shm_str_dup and shm_asciiz_dup set the destination buffer to NULL if
  - Convert all relative pathnames of files to absolute with
  - modified function get_pathname to return path relative to the
  - support for setting the source address in tcp_send() and tcpconn_get()
  - updated all the child_init users to ignore or treat specially the
  - added low_mem_threshold1 & low_mem_threshold2 (the ammount of free memory
  - tls: tls_update_fd improvement - use SSL_set_fd only when the connection is
  - workaround for openssl bug #1491 (multiple problems on low memory): tls
  -  malloc debugging for openssl and random malloc null returns turened off
  - added tls module documentation (not yet complete, still missing select, rpc and better tls.cfg description).
  - make tar doesn't exclude tls*, but instead tls/*
  - call tls_shutdown() only if tls_set_fd() was succesfull
  - tls: openssl kerberos malloc bug (# 1467) fixed on cvs (0.9.8e-dev and 0.9.9-dev), so add extra checks for enabling the workarround (which disables kerberos) only when necessary:  if openssl compiled with kerberos support, and openssl < 0.9.8e-beta1 or openssl between 0.9.9-dev and 0.9.9-beta1 apply workarround.
  - tls-core.patch removed (no longer necessary)
  ...