Feature/invitation

Merge request contains:

• Prototype Dialog (can be used for all Usecases) (Screenshot)
• Dialog animates on show and hide
• Dialog is layouted based on InvitationOption
• Tests for Encryption

Make the changes visible in the App: Add the following lines in the viewWillAppear(animated:) in SendViewController Or somewhere else in the Code (keep in mind self needs to be a ViewController, that is fully loaded)

InvitationDialogViewController.present(on: self, animated: true)

enzevalos_iphone/Assets.xcassets/ic_secure_card.imageset/Contents.json

+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "filename" : "ic_secure_card.png",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "filename" : "ic_secure_card@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "filename" : "ic_secure_card@3x.png",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  },
+  "properties" : {
+    "template-rendering-intent" : "template"
+  }
+}
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