Feature Request: Allow "loadpage.html" to be customized.

[PeetMcK]

Issue:
Without network Xcreds defaults to the contents of "/Library/Security/SecurityAgentPlugins/XCredsLoginPlugin.bundle/Contents/Resources/loadpage.html" which simply displays "Please Wait....(or try connecting to network or check preferences)"

Feature Request:
Allow for a custom HTML page to load, either by embedding the HTML code directly in the profile, or by redirecting the the page to another location on disk, or as an option for configuration.

Possible issue:
If the file is redirected locally, it may be worth while to at least check permissions on the custom HTML file incase someone accidentally points it to a world-writable file. I could se this going poorly if discovered in a lab environment. But I do think it would be useful and more flexible to allow for redirections as well as HTML embedded in the profile. Mutually exclusive as only one method of customization should work, e.g. Profile HTML overrides a redirect in the same profile.