Trivial: Remove useless string_to_bool()
Trivial: Remove useless string_to_bool()

string_to_bool() is not used by anyone.
Furthermore, it is not well designed. It tries to convirt 't', '1'
to True, which could be confused.

So remove it. If we need something similar, let's make a better one.

Change-Id: Ic1f63480c806bf7bcc9f541fc806eed297ddf718

dtroyer/osc-lib