fixed relative links in request email

Conflicts:
	app/views/admin_mailer/request_filed.html.erb
move mailer hostname config to environment files
updated README with mailer link instructions
added link hostname config to test.rb
update Announcement form
render announcement message with Markdown
Merge pull request #1029 from YaleSTC/1027_announcement_links_master

resolves #1027
Merge pull request #1024 from YaleSTC/1017_request_email_links_master

resolves #1017
updated CHANGELOG w/ v3.4.8 changes
added email link hostname config to staging.rb
removed erroneous spaces from equipment import instructions
Merge branch 'master' into 2_authentication_II

Conflicts:
	README.md