First attempt at getting the signs of cells to display information #31

The variables possible are:
* %player% - the player's last known name
* %uuid% - the player's uuid, or what can fit on a sign
* %reason% - the reason the player was jailed
* %jailer% - the person/thing who jailed this player
* %afktime% - the amount of time the player has been afk
* %timeinminutes% - the amount of remaining time the player has in
minutes

If the player is jailed forever, then it pulls from the language file
`jailedforeversign` property.

src/main/java/com/graywolf336/jail/beans/Cell.java

@@ -72,6 +72,11 @@ public class Cell {
     public HashSet<SimpleLocation> getSigns() {
         return this.signs;
     }
+    
+    /** Checks if there are any signs for this cell. */
+    public boolean hasSigns() {
+    	return !this.signs.isEmpty();
+    }
 
     /** Returns the entire list of signs in a string. */
     public String getSignString() {

src/main/java/com/graywolf336/jail/beans/Prisoner.java

@@ -112,7 +112,7 @@ public class Prisoner {
 
     /** Gets the remaining time the prisoner has in minutes. */
     public long getRemainingTimeInMinutes() {
-        return TimeUnit.MINUTES.convert(time, TimeUnit.MILLISECONDS);
+    	return TimeUnit.MILLISECONDS.toMinutes(time);
     }
 
     /** Gets the remaining time the prison has in minutes except only in int format. */