loggingTools: fix CapturingLogHandler to work with py37
loggingTools: fix CapturingLogHandler to work with py37

we can't set the logger.level directly because in py37 the logger has a _cache
attribute and that needs to be invalidated by calling setLevel method.

also, I noticed we weren't restoring the original 'disabled' attribute value...

And we need to also set/restore the 'propagate' attribute.

googlefonts/fonttools,fonttools/fonttools