Merge branch 'profiles' into development

* profiles:
  Update Changelog for the profiles branch
  Add SSL presets.
  Implement sig_hashes
  Create API for mbedtls_ssl_conf_sig_hashes().
  Small internal changes in curve checking
  Extra check in verify_with_profile()
  Clarify a point in the documentation
  Fix define for ssl_conf_curves()
  Add mbedtls_ssl_conf_cert_profile()
  Implement cert profile checking
  Change data structure of profiles to bitfields
  Add pre-defined profiles for cert verification
  Create cert profile API (unimplemented yet)
  Remove duplicated tests for x509_verify_info()
  Add tests for dhm_min_bitlen
  Add dhmlen option in ssl_client2.c
  Add ssl_conf_dhm_min_bitlen()