GitHub Components MD docs clean up (#324)

* hideBanner Private to Pubic method change and rename

_hidebanner is private method not public
As public should be hideBanner() not private _hideBanner()
Renamed methods as no other component included component name in their
public methods

* Moved hide code location under show() and removed overlooked underscore

* Remove white space and rename event handler

Removed white spaces as per gulp warnings.
Updated event handler method name in _setListners with new method name
'hide', was '_hide'

* Reinstated showBanner()

Reinstated showBanner() as deprecated method, as not to break existing
dep.
Calls new method show()

* Update HB/Docs & Test fix for GitHub .md pages showing inline <script> tags

Update HB/Docs & Test fix for GitHub .md files all showing <script> tags
at bottom of all .md pages

* Revert "Update HB/Docs & Test fix for GitHub .md pages showing inline <script> tags"

This reverts commit 3be0502.

* Update HB/Docs & Trial fix GitHub .md pages showing inline <script> tags

Update HB/Docs & Test fix for GitHub .md files showing <script> tags
at bottom of all .md pages on github site and also tested with two
online editors and they also show <script> as plain text

* .md file cleanup

Button , Callout, CheckBox, ChoiceFieldGroup, CommandBar,CommandButton,
ContextualMenu, Dialog & MessageBanner

* GHDocs Components Clean Up

Decoded html encoded strings back to tags.
FacePile.md still needs work

* GHDocs Compnents MarkDown Cleanup

Edited all components MD
Note: Dialog Component MD needing help to fix broken Button layout

* Fix Dialog MarkDown

Found format error

* Fixed Dialog.md

Located example, and fixed as per component html example

ghdocs/components/Dialog.md

@@ -87,14 +87,12 @@ This component has only the default state.
             </div>
         </div>
         <div class="ms-Dialog-actions">
-            <!--- Needs fixing -->
             <button class="ms-Button ms-Dialog-action ms-Button--primary">
-                <button class="ms-Button ms-Dialog-action">
-                    <span class="ms-Button-label">Save</span>
-                </button>
-                <button class="ms-Button ms-Dialog-action">
-                    <span class="ms-Button-label">Cancel</span>
-                </button>
+                <span class="ms-Button-label">Save</span>
+            </button>
+            <button class="ms-Button ms-Dialog-action">
+                <span class="ms-Button-label">Cancel</span>
+            </button>
         </div>
     </div>
 	```