Use %PROGRAMFILES% instead of $(runtime.programFiles) for service…

… exe paths. (Azure#1718)

We have reports that the CAB installer in Windows 10 16299 and
Hyper V Server 2016 14393 does not expand `$(runtime.programFiles)` in
the paths of the service executables.

So just like 87957c9, this commit changes them
to use the `%PROGRAMFILES%` env var that gets resolved at runtime.

This commit also puts the path in double-quotes, though it somehow worked fine
even without them even though there is a space in `C:\Program Files`.

It also puts the `%PROGRAMDATA%` components added in
87957c9 in double-quotes, though that env var
doesn't have spaces on any Windows version that we know of anyway.

Fixes Azure#1528

edgelet/build/windows/iotedge.wm.xml

@@ -44,7 +44,7 @@
     description="Moby Engine"
     displayName="Moby Engine"
     errorControl="normal"
-    imagePath="$(runtime.programFiles)\iotedge-moby\dockerd.exe -H npipe:////./pipe/iotedge_moby_engine --exec-opt isolation=process --run-service --data-root %PROGRAMDATA%\iotedge-moby --exec-root %PROGRAMDATA%\iotedge-moby\exec-root"
+    imagePath=""%PROGRAMFILES%\iotedge-moby\dockerd.exe" -H npipe:////./pipe/iotedge_moby_engine --exec-opt isolation=process --run-service --data-root "%PROGRAMDATA%\iotedge-moby" --exec-root "%PROGRAMDATA%\iotedge-moby\exec-root""
     name="iotedge-moby"
     objectName="LocalSystem"
     sidType="unrestricted"
@@ -57,7 +57,7 @@
     description="Azure IoT Edge Daemon"
     displayName="Azure IoT Edge Daemon"
     errorControl="normal"
-    imagePath="$(runtime.programFiles)\iotedge\iotedged.exe -c %PROGRAMDATA%\iotedge\config.yaml"
+    imagePath=""%PROGRAMFILES%\iotedge\iotedged.exe" -c "%PROGRAMDATA%\iotedge\config.yaml""
     name="iotedge"
     objectName="LocalSystem"
     sidType="unrestricted"