Added SideMenu_SlidingTabs app source

I added the sample source code. I also sent you an email with the following contents:

Ok, I created the sample app. The directory is a little strange because of Android Studio, but I left out all of the auto-generated unnecessary stuff.

- I want to add a readme, explaining the app a little bit. Should I add that in the directory or just edit readme file.
- Is it ok if I add two screen shots in the root of the app? I don't know if people usually do that, but I was want people to preview it before downloading the code.