Fisheye should index file content for branches other than trunk

Currently Fisheye is designed to only index file content for files located on trunk.
This was a choice made with consideration for performance eg. indexing file content for repos with many branches would be expensive and delay the process.

However in the search UI there is a branch drop down which gives the impression that file content can be searched on other branches besides trunk.

Furthermore, in the case of Git repos, file content for branches other than main/master is indexed.

This feature request is a suggestion to implement similar functionality across all feasible DVCS supported by Fisheye.