dovecot: Enable the body Sieve extension

In order to use tests like `body :content "text/plain" :contains "Reassigned Issue"`.

roles/dovecot/templates/dovecot.conf.j2

@@ -10,8 +10,8 @@ namespace inbox {
 	hidden = no
 	inbox = yes
 	list = yes
-	location = 
-	prefix = 
+	location =
+	prefix =
 	separator = .
 	type = private
 
@@ -44,7 +44,7 @@ plugin {
 	sieve = ~/.dovecot.sieve
 	sieve_dir = ~/.sieve
 	# fileinto and mailbox is required by the global spam-to-folder.sieve script
-	sieve_extensions = duplicate envelope fileinto imap4flags mailbox regex variables
+	sieve_extensions = body duplicate envelope fileinto imap4flags mailbox regex variables
 	sieve_global_dir = /etc/dovecot/sieve/global/
 	sieve_global_path = /etc/dovecot/sieve/default.sieve
 	sieve_before = /etc/dovecot/sieve/spam-to-folder.sieve