Add support for Swift 3.0

Sources/Filters.swift

@@ -1,4 +1,4 @@
-func toString(value: Any?) -> String? {
+func toString(_ value: Any?) -> String? {
   if let value = value as? String {
     return value
   } else if let value = value as? CustomStringConvertible {
@@ -8,25 +8,25 @@ func toString(value: Any?) -> String? {
   return nil
 }
 
-func capitalise(value: Any?) -> Any? {
+func capitalise(_ value: Any?) -> Any? {
   if let value = toString(value) {
-    return value.capitalizedString
+    return value.capitalized
   }
 
   return value
 }
 
-func uppercase(value: Any?) -> Any? {
+func uppercase(_ value: Any?) -> Any? {
   if let value = toString(value) {
-    return value.uppercaseString
+    return value.uppercased()
   }
 
   return value
 }
 
-func lowercase(value: Any?) -> Any? {
+func lowercase(_ value: Any?) -> Any? {
   if let value = toString(value) {
-    return value.lowercaseString
+    return value.lowercased()
   }
 
   return value