Use internal AGS for print task server

This print server won't be available to users who clone the repo
which will be an incentive to provide their own server settings.
It also enables us to use custom print templates which we've created
locacally.
Add mxd printing templates with custom layout

These are modified versions of the default "Letter ANSI A Landscape"
and "Letter ANSI A Portrait" mxds that ship with AGS, providing more
room for a multicolumn legend, a logo and optimized map spacing.
Files with "Legend" in their name, occupy the legend space with the
map.
Remove PageSize and fixup UI markup

PageSize is no longer a parameter for printing, we assume Letter ANSI A
size.  This was to support custom printing, which requires new templates
to be created, so we dropped support for the less used sized.

Also cleaned up the markup so it wouldn't rely so heavily on floats and
paddings to achieve the layout, and closed input tags correctly
Add optional print template prefix to settings

If left blank, the framework will try to load the default AGS print
template
but if set, uses the value to construct the template name to use.
Allow for custom templates in export
Merge pull request #196 from mmcfarland/topic/detailed-printing

Detailed printing
Add support for blacklisting identify attributes

Certain attributes do not provide meaningful data, so this feature allows those attributes to be blacklisted so they can be removed from the output.

As of this commit, you CANNOT blacklist display values, which are very similar to attributes, so it may create the appearance of attributes that cannot be blacklisted.
Merge pull request #197 from steventlamb/topic/identify_blacklist

Add support for blacklisting identify attributes
Fix syntax error in region.json

elementId was written as a javascript style object key (symbol) instead of a json object key (string). This would crash for any strict JSON parsers that closely follow the JSON spec.
Add downloadUrl property to layer_selector plugin configuration.

You can now specify a downloadUrl property on layers defined in the showLayers group for AGS sources, and the layerIds group for WMS sources. This will add a button next to the layer name with the specified URL.

For AGS dynamic services without a showLayers group, add a new group called layerMetaData. This group closely resembles showLayers but is sparsely populated. Properties in this group will be merged with the original layers data source.
Merge pull request #199 from kdeloach/topic/download-layer-info

Add downloadUrl property to layer_selector plugin configuration.
Create Logging module.

Move logger creation logic to its own module so it can be reused on other components.
Add support for async PrintTask on export.

Check ArcGIS REST API to see if we can create an asynchronous PrintTask
to avoid timing out during export.
Retry export up to 5 times if there is a failure.
Lower retry failed export attempts to 3.
Add pane number to export dialog title.
Merge pull request #200 from kdeloach/topic/export-stability

Add support for async PrintTask and automatic export retry upon failure