added CreateFilePath method to IFileStorage and used it after file chooser for save

-> save as works with GDrive as well

minor changes and fixes

src/Kp2aBusinessLogic/Io/BuiltInFileStorage.cs

@@ -200,5 +200,12 @@ namespace keepass2android.Io
 		{
 			return ioc.GetDisplayName();
 		}
+
+		public string CreateFilePath(string parent, string newFilename)
+		{
+			if (!parent.EndsWith("/"))
+				parent += "/";
+			return parent + newFilename;
+		}
 	}
 }

src/Kp2aBusinessLogic/Io/CachingFileStorage.cs

@@ -481,6 +481,11 @@ namespace keepass2android.Io
 			return _cachedStorage.GetDisplayName(ioc);
 		}
 
+		public string CreateFilePath(string parent, string newFilename)
+		{
+			return _cachedStorage.CreateFilePath(parent, newFilename);
+		}
+
 
 		public string GetBaseVersionHash(IOConnectionInfo ioc)
 		{

src/Kp2aBusinessLogic/Io/IFileStorage.cs

@@ -150,6 +150,10 @@ namespace keepass2android.Io
 		/// Converts the given path to a displayable string
 		/// </summary>
 		string GetDisplayName(IOConnectionInfo ioc);
+
+		//returns the path of a file "newFilename" in the folder "parent"
+		//this may create the file if this is required to get a path (if a UUID is part of the file path)
+		string CreateFilePath(string parent, string newFilename);
 	}
 
 	public interface IWriteTransaction: IDisposable

src/Kp2aBusinessLogic/Io/JavaFileStorage.cs

@@ -280,6 +280,11 @@ namespace keepass2android.Io
 			return _jfs.GetDisplayName(ioc.Path);
 		}
 
+		public string CreateFilePath(string parent, string newFilename)
+		{
+			return _jfs.CreateFilePath(parent, newFilename);
+		}
+
 		private DateTime JavaTimeToCSharp(long javatime)
 		{
 			return new DateTime(1970, 1, 1).AddMilliseconds(javatime);