Implement New Icons

[edenworky]

in PNG:

collaborator overview 16X16 in both colors: https://slack.global.ssl.fastly.net/66f9/img/team_directory_icons.png
add project 18x24 #645563 #fff
new milestone 18x24 #645563 #fff
project status 18x24 #645563 #fff

add-collab-project-purple
add-collab-project-white
add-project-purple
add-project-white
collaborator-overview-purple
collaborator-overview-white
project-status-purple
project-status-white
sprite-collborator-overview
submit-milstone-purple
submit-milstone-white