Integrate Existing Splash component into the web-mapping-components core library

Currently both the population-viewer and the proximity-viewer duplicate a lot of code to generate a splash window on their respected viewer apps. Note: The only difference between the two files is one has an added class to the window.

To minimize code duplication, a generic splash module should be added to the web-mapping-components core library, and all viewers should use that built-in table component.

• population-viewer splash.js file
• proximity-viewer splash.js file

Currently the Splash component has hard coded nls localized strings in the splash template. This needs to become more generic, allowing a user to configure a splash window's content when the Splash component is instantiated.