Log Message:
Update to 1.3.1:

Serf 1.3.1 [2013-08-15, from /tags/1.3.1, r????]
  Fix issue 77: Endless loop if server doesn't accept Negotiate authentication.
  Fix issue 114: ssl/tls renegotiation fails
  Fix issue 120: error with ssl tunnel over proxy with KeepAlive off and
                 Basic authentication.
  Fixed bugs with authentication (r2057,2115,2118)
  SCons-related fixes:
   Fix issue 111: add flag to set custom library path
   Fix issue 112: add soname
   Fix issue 113: add gssapi libs in the serf pc file
   Fix issue 115: Setting RPATH on Solaris broken in SConstruct
   Fix issue 116: scons check should return non-zero exit staths
   Fix issue 121: make CFLAGS, LIBS, LINKFLAGS and CPPFLAGS take a space-
                   separated list of flags.
   Fix issue 122: make scons PREFIX create the folder if it doesn't exist
   Mac OS X: Fix scons --install-sandbox
   Solaris: Fix build with cc, don't use unsupported compiler flags
  Require SCons version 2.3.0 or higher now (for the soname support).

Serf 1.3.0 [2013-07-23, from /tags/1.3.0, r2074]
  Fix issue 83: use PATH rather than URI within an ssltunnel (r1952)
  Fix issue 108: improved error reporting from the underlying socket (r1951)
  NEW: Switch to the SCons build system; retire serfmake, serf.mak, autotools
  Improved Basic and Digest authentication:
    - remember credentials on a per-server basis
    - properly manage authentication realms
    - continue functioning when a server sets KeepAlive: off
  Windows: add support for NTLM authentication
  Improved 2617 compliance: always use strongest authentication (r1968,1971)
  Fixed bugs with proxy authentication and SSL tunneling through a proxy
  Fixed bugs the response parser (r2032,r2036)
  SSL connection performance improvements
  Huge expansion of the test suite