Use the minimal CEF distribution

It's 1/2 or 1/5 (for Windows and Linux respectively) the size of the
standard distribution, compressed.

However, its CMakeLists.txt is an example for including into clients'
configs, and doesn't work with ExternalProject_Add, so ship a slightly
modified CMakeLists.txt to replace it (the only difference is the
cefsimple and cefclient include_directory lines have been removed).

scripts/cmake/CEF_CMakeLists.txt

@@ -0,0 +1,20 @@
+# Copyright (c) 2014 The Chromium Embedded Framework Authors. All rights
+# reserved. Use of this source code is governed by a BSD-style license that
+# can be found in the LICENSE file.
+
+cmake_minimum_required(VERSION 2.8.12.1)
+
+set(CMAKE_CONFIGURATION_TYPES Debug Release)
+
+project(cef)
+
+set_property(GLOBAL PROPERTY OS_FOLDERS ON)
+
+set(CEF_ROOT "${CMAKE_CURRENT_SOURCE_DIR}")
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CEF_ROOT}/cmake")
+
+find_package(CEF REQUIRED)
+
+add_subdirectory(${CEF_LIBCEF_DLL_WRAPPER_PATH} libcef_dll_wrapper)
+
+PRINT_CEF_CONFIG()