add bugzilla integration hook. example of writing hook in python.
hook updates bugzilla bugs when it sees commit comments that mention
bug id, such as "i fixed bug 77".
only bugzilla 2.16 supported yet, but easy to extend. bugzilla versions
have different schema, i have not used later than 2.16.
<item>
<title>#desc|strip|firstline|strip|escape#</title>
<link>#url#?f=#filenode|short#;file=#file|urlescape#</link>
<description><![CDATA[#desc|strip|escape|addbreaks#]]></description>
<author>#author|obfuscate#</author>
<pubDate>#date|rfc822date#</pubDate>>
</item>