Scaffold and solution challenge 07 not working with latest angr

[Benoit Sevens]

Scaffold and solution challenge 07 are not working with latest angr, because SimFile class changed.

This is working code with latest version of angr for the filesystem part:

  filename = "OJKSQYDP.txt"  # :string
  symbolic_file_size_bytes = 64

  password = claripy.BVS('password', symbolic_file_size_bytes * 8)
  password_file = angr.storage.SimFile(filename, content=password, size=symbolic_file_size_bytes)

  initial_state.fs.insert(filename, password_file)
  simulation = project.factory.simgr(initial_state)