Add desktop theme support for RDP

Adding support for desktop wallpaper, animations, window drag, themes,
smooth fonts, window decorations and gdi plus drawing. Also adding
support for the connection type setting since desktop theming is
disabled by default over slower RDP connections.

New RDP settings for user-mapping.xml:

* disable-wallpaper (true/false)
* disable-theming (true/false)
* disable-menu-animations (true/false)
* disable-full-window-drag (true/false)
* smooth-fonts (true/false)
* desktop-composition (true/false)
* decorations (true/false)
* draw-gdi-plus (true/false)
* connection-type (broadband_low, satellite, broadband_high, wan, lan)