Email icons

Get the hashed paths for icons when emailing
Merge pull request #932 from simong/email-hashed-icons

Email icons
Use new location of i18n keys
Reverted back to `ACTIVITY_` keys
Only load properties from the bundles directory
Merge pull request #933 from nicolaasmatthijs/emailI18N

Email i18n improvements
(Issue 934) Apply hashing to logo
(Issue 937) Use min and max height for logo
Follow up on institutional logo size limit
Don't link to users profile path in comments and header of email if the profile isn't public
Merge pull request #939 from bp323/issue-3778

Don't link to the user's profile if it's not public in emails