Make font_manager ignore KeyErrors for bad fonts

[dmcdougall]

Fixes #1601.

[dmcdougall]

There are other try/except blocks in the file that do:

except:

and not even

except Exception:.

This should probably be updated. Perhaps in a different pull request.

[mdboom]

I agree about the other empty try / except blocks -- but that can be a separate PR. This fixes a real issue (in #1601).

[dmcdougall]

@mdboom That's what I thought. In that case this is ready to go. The Travis failure was a git clone timeout on Python 3.1, so nothing to worry about. The tests pass on Python versions 2.{6,7} and 3.2.

[dmcdougall]

Cheers @mdboom!