Added "Finish Drawing" button for touch devices.

Button is shown only for touch devices when the draw polygon or polyline buttons are activated.

![screenshot](http://i.imgur.com/VZr3vI8.png)

I believe that this will prevent the issue in #179.

Closes #179

Polished up error reporting related to shape search.

Also decreased selection marker symbol size.
Merge pull request #191 from agrc/drawing

Added "Finish Drawing" button for touch devices.