slide: Added slide potentiometer sensor C source

Added the C source for the flex sensor with necessary changes to cmake,
examples, and docs.

    * Renamed all files with groveslide to slide
    * Replaced all instances of groveslide with slide
    * Added C source for slide sensor
    * Updated all cmake files
    * Added C example for slide sensor
    * Split out slide sensor from grove library

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/slide/javaupm_slide.i

@@ -0,0 +1,19 @@
+%module javaupm_slide
+%include "../upm.i"
+
+%{
+    #include "slide.hpp"
+%}
+
+%include "slide.hpp"
+
+%pragma(java) jniclasscode=%{
+    static {
+        try {
+            System.loadLibrary("javaupm_slide");
+        } catch (UnsatisfiedLinkError e) {
+            System.err.println("Native code library failed to load. \n" + e);
+            System.exit(1);
+        }
+    }
+%}