SessionsModal.js creation

[amybarger]

Have a general layout and beginning workings for the SessionsModal.js. This modal is meant to provide a session summary between the mentor and mentee when their name is clicked on in the calendar. The beginnings of state management and styles are in this PR.

Trello: https://trello.com/c/sAQ4to4S/74-modal-for-session-details

Type

• This is a bug fix
• [x ] This is a new feature
• This refactors a feature
• This is to improve performance

Review

• [x ] Is this a work in progress?
• [x ] Is this ready to be reviewed?
• [x ] Have you added two reviewres to this pull request and dropped a message in slack?

[MustafaCajib]

Looks good!!