added overloads for SharpFileSystem.Open and .Create to take a password for the zip file
re-used unit tests from SharpFileSystemTests as well as added unit tests to verify that a file can be opened when the correct password is in use, and that an exception is thrown when trying to open a file with the wrong password.
added overloads for SharpFileSystem.Open and .Create to take a password for the zip file re-used unit tests from SharpFileSystemTests as well as added unit tests to verify that a file can be opened when the correct password is in use, and that an exception is thrown when trying to open a file with the wrong password.