Proposal page improvements

[bourque]

Some potential improvements:

• [ ] Add exposure number to mouseover panel (if not enough room, remove exposure date)
• [x] Default sort by should be by observation date
• [ ] Proposal status/information should be placed before sorting options

Credit Jo Taylor for some of these suggestions!

[bhilbert4]

Current default sort is reverse chronological (newest first).

Exposure number addition is covered in #1019

[bhilbert4]

Adding info to the mouseover is captured in #1019 Moving the proposal status above the sorting options will not be done at this time.