Added MockFile.AppendText Implementation with unit test.
Merge pull request #53 from Sutikshan/master

Added MockFile.AppendText Implementation with unit test.
Add a unit test for MockFileInfo.OpenRead
Add implementation of MockFileInfo.OpenText
Merge pull request #54 from dirkrombauts/master

Add implementation of MockFileInfo.OpenText
Implement MockDirectoryInfo.GetFileSystemInfos methods