add function to generate Apple's style password

Cartfile

@@ -4,4 +4,3 @@ github "mssun/objective-git" "master"
 github "zahlz/SwiftPasscodeLock" "master"
 github "bitserf/FavIcon"
 github "kishikawakatsumi/KeychainAccess" "master"
-

pass/Helpers/DefaultsKeys.swift

@@ -17,9 +17,6 @@ extension DefaultsKeys {
     
     static let pgpPublicKeyArmor = DefaultsKey<String?>("pgpPublicKeyArmor")
     static let pgpPrivateKeyArmor = DefaultsKey<String?>("pgpPrivateKeyArmor")
-//    
-//    static let pgpPrivateKeyURLPassphrase = DefaultsKey<String?>("pgpPrivateKeyURLPassphrase")
-//    static let pgpPrivateKeyArmorPassphrase = DefaultsKey<String?>("pgpPrivateKeyArmorPassphrase")
     static let pgpKeyID = DefaultsKey<String?>("pgpKeyID")
     static let pgpKeyUserID = DefaultsKey<String?>("pgpKeyUserID")
     
@@ -36,5 +33,12 @@ extension DefaultsKeys {
     static let passcodeKey = DefaultsKey<String?>("passcodeKey")
     
     static let isHideUnknownOn = DefaultsKey<Bool>("isHideUnknownOn")
+    
+    static let passwordGenerationMethod = DefaultsKey<String>("passwordGenerationMethod")
 
+    func initDefaultKeys() {
+        if Defaults[.passwordGenerationMethod] == "" {
+            Defaults[.passwordGenerationMethod] = "Random"
+        }
+    }
 }

pass/Helpers/Utils.swift

@@ -37,6 +37,17 @@ class Utils {
         return lastUpdatedTimeString
     }
     
+    static func generatePassword(length: Int) -> String{
+        switch Defaults[.passwordGenerationMethod] {
+        case "Random":
+            return randomString(length: length)
+        case "Keychain":
+            return Keychain.generatePassword()
+        default:
+            return randomString(length: length)
+        }
+    }
+    
     static func randomString(length: Int) -> String {
         
         let letters : NSString = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"