Removed broken layers; Added attribution.
Reformatted xaml; Added comments to code.
Merge pull request #39 from Esri/akajanus-nuget-api-reference

Changed samples to use NuGet instead of SDK reference.
Added attribution to Store/Phone for WebTiledLayers sample
Removed Weblayer.Copyright and moved everything to Attribution blocks in xaml.
Added note to description regarding Attribution code.
Merge pull request #40 from Esri/kdalton/webtiledlayersample

Removed broken layers; Added attribution.
Fixed check for sdk installation