Add desensitizing panel

This popup panel desensitizes (grays out) the window behind it. Click its "OK" button to sensitize window.
Display a reminder to sign in to use WMT

Use a DesensitizingPopupPanel.
Update password help email

Use CSDMSsupport@colorado.edu instead of mark.piper@colorado.edu.
Add CSDMS support email to help and signin dialogs

Make it easier for users to contact us if something is amiss.
Merge pull request #72 from mdpiper/styling-and-appearance

Add desensitizing panel when user isn't signed in