CC3200 FS refactoring and basic Mongoose example

Moved filesystem-related code out of SJS and into common.
Made it possible to have one, both or no filesystems enabled.
FailFS is now SimpleLinkFS, SLFS (ahem).

Example just serves a "Hello, world!" index page for now.

PUBLISHED_FROM=0e98ee4b8d95782c10791522c42eae5a7ba314f9

examples/CC3200/slfs/index.html

@@ -0,0 +1,7 @@
+<!DOCTYPE HTML>
+<html>
+  <head></head>
+  <body>
+    <h1>Hello, world!</h1>
+  </body>
+</html>