Define intro and outro slide options

[meganem]

What do we need/want in an intro and outro slide? How does the user add this information? Need to develop a UI in Edit Presentation mode for this.

[meganem]

Title Slide:

• presentation title
• date, name, other info (must support multiple lines)
• image background, or a color?

Ending Slide:

• Slide title (defaults to "Thank you!")
• other text, like name, contact info (must support two lines)
• image background, or color?

For the UI, add two links to the Edit Presentation menu to allow for editing these two slides.

Later: consider offering multiple templates for these slides...