Added sample Web map by ID

- This closes #5 from the Maps from ArcGIS.com category
Added sample Web map using JSON

- This closes #6 from the Maps from ArcGIS.com category
Added missing .js files to Web map by ID

- extra .js files to close #5
Added sample Geodesic buffers with ArcGIS.com map

- This closes #4 Geodesic buffer with AGOL map
Minor fixes

- updated variable on index page
- committed overviewMapWidget .js files
Merge pull request #114 from amarinelli/master

Added 3 samples & minor fixes