Add a new command /jail time which has easy access for add/subtract

time from a prisoner's sentence.

This command could be useful for commandblocks or something else, as it
does not need a player context. This closes Bukkit Dev Ticket:
http://dev.bukkit.org/bukkit-plugins/jail/tickets/432/

src/main/java/com/graywolf336/jail/enums/LangString.java

@@ -60,6 +60,8 @@ public enum LangString {
 	OFFLINEJAIL ("jailing"),
 	/** The message sent to the jailer when they jail someone who is online. */
 	ONLINEJAIL ("jailing"),
+	/** The message sent when finding out how much time a prisoner has. */
+	PRISONERSTIME ("jailing"),
 	/** The message sent to the prisoner when they try to do something but it is protected. */
 	PROTECTIONMESSAGE ("jailing"),
 	/** The message sent to the prisoner when they try to do something and it is protected, but no penalty. */