Tape Recorder plots failing after recent history string update

[justin-richling]

ADF run type

Model vs. Model

What happened?

After PR #310 the Tape Recorder plots are failing due to incorrect ADF object history string returns.

File "/glade/work/richling/ADF/ADF/lib/../scripts/plotting/tape_recorder.py", line 40, in tape_recorder
    hist_str = adfobj.hist_string
  File "/glade/work/richling/ADF/ADF/lib/adf_info.py", line 636, in hist_string
    return self.__hist_str
AttributeError: 'AdfDiag' object has no attribute '_AdfInfo__hist_str'

ADF Hash you are using

c715fc1

What machine were you running the ADF on?

CISL machine

What python environment were you using?

NPL (CISL machines only)

Extra info

I have a fix, will create PR