config: point people to obj/autoconf.err when psol isn't detected by ./configure
Merge pull request #592 from pagespeed/jefftk-better-configure-error

config: point people to obj/autoconf.err when psol isn't detected
readme: release 1.7.30.2
native-fetcher: add support for FetchProxy

The native fetcher previously ignored FetchProxy settings; now it doesn't.

Squash-merge of tcpper's #590.
merge pagespeed master