check in binaries for known-good dafny & z3, and a git submodule for vale

these binaries correspond to:
z3 release 4.5.0 x64 windows

dafny commit 28bf5d11ce1a8dc5663f1f9d04c721acae12403f
    Author: qunyanm <qunyanm@hotmail.com>
    Date:   Fri Jan 27 21:02:58 2017 -0800
        Fix incorrect translation of forallstmt

(experience suggests that trying keep track of support for multiple
versions of dafny or z3 is unproductive)

.gitmodules

@@ -0,0 +1,4 @@
+[submodule "tools/vale"]
+	path = tools/vale
+	url = https://github.com/project-everest/vale.git
+	branch = komodo

Makefile

@@ -7,8 +7,8 @@ PREFIX ?= arm-eabi-
 INSTALLDIR ?= .
 GUEST_KERNEL ?= kernel7.img
 GUEST_DISKIMG ?= raspbian.img
-VALE ?= vale.exe
-DAFNY ?= Dafny.exe
+VALE ?= tools/vale/bin/vale.exe
+DAFNY ?= tools/dafny/Dafny.exe
 #-----------------------------------------------------------------------------
 
 AS = $(PREFIX)as

tools/dafny/LICENSE.txt

@@ -0,0 +1,24 @@
+Dafny
+
+Copyright (c) Microsoft Corporation
+
+All rights reserved.
+
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the ""Software""), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED *AS IS*, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

tools/vale

@@ -0,0 +1 @@
+Subproject commit 5c3e8a8deb3ef27d8614806bb00635788bd6d380