bundle-spec: properly parse boolean configuration as boolean
Before this changesets "v2;revbranchcache=no" would actually request the
addition for a revbranchcache part as the non-empty string `"0"` is `True`
#require test-repo jshint hg10
$ . "$TESTDIR/helpers-testrepo.sh"
run jshint on all tracked files ending in .js except vendored dependencies
$ cd "`dirname "$TESTDIR"`"
$ testrepohg locate 'set:**.js' \
> 2>/dev/null \
> | xargs jshint