Squashed commit of the following:

commit 610ed879d57785cb0457f7f127889496d325f732
Author: Andreas Huber <andih@google.com>
Date:   Fri Nov 19 09:28:52 2010 -0800

    HTTP header keys are to be treated case insensitive.

    Change-Id: I9690880528a6b0f611958de7996c2753948a03c3

commit 554a2499a293d8d53907d01d972a9cfe9b92738e
Author: Andreas Huber <andih@google.com>
Date:   Fri Nov 19 09:22:45 2010 -0800

    Remove one more legacy "string" implementation.

    Change-Id: I7638d849427a39bbc040082a8663b3b9b81a632b

Change-Id: I626a60abdcd1dd6403be880dad4d0499d77ca71f