Various content updates for 2018 Speakers

[mmmavis]

• Related to #1132 - updated times for some speakers' talks
• Related to #1130 - added Tim to 2018 speakers & updated time for Renee's talk

[mmmavis]

@KevZawacki can you verify that I have covered everything you mentioned in #1130 and #1132? 👀

• https://mozillafestival-org-st-pr-1133.herokuapp.com/
• https://mozillafestival-org-st-pr-1133.herokuapp.com/speakers

[KevZawacki]

Hi @mmmavis,

Perfect 👍 It's all there. Thank you!