Here’s a link that will be helpful in the future. Trac is a great alternative to bug tracking for various reasons (one being the interface actually having some great flow to it). Mantis is a cumbersome mess when it comes to layouts, but there are templates out there, but I find tracd a better alternative.
Here’s a link to a tutorial on how to get trac up and running with little to no effort. Remember, user rights is extremely important with this system, so do not skip over them.
Also remember to place .git in the repository directory when you install the plugin. Going the route above will save headaches instead of editing straight from the config file.
Also for filesize upload issues, you are going to have to change a setting in the /path/to/trac/env/conf/trac.ini which will be at the very top. Just change the max_size number for [attachment] AND [wiki](otherwise the files will not display in the trac interface) to suit your needs for uploaded files.