Include local copy of HTML::Email::Obfuscate
The HTML::Email::Obfuscate perl module is not commonly installed
but provides an added defence against email scraping.
Include a local copy of HTML::Email::Obfuscate and adjust the
gitweb_config.perl script to find it for gitweb.cgi. Also tweak
the perl module checker to warn about a dependency but no longer
warn about HTML::Email::Obfuscate itself.
Since one of the HTML::Email::Obfuscate license options is GPLv2
there is no license conflict created by including a copy.