[enhance] add a link to signature
[feature] add signature to reply emails
[workaround]fix MailCore for iOS SDK 8.1
[fix] fix template engine bug
[fix] use latest MailCore for the SDK 8.1 support
[fix] template engine bug
add signature template
[fix]update MailCore version
Merge branch 'dev' of github.com:ninjaatif/idealab_client into dev