svnwrap: improve a docstring & a comment. The docstring for SubversionRepo was technically inaccurate; not only do we require Subversion 1.5, but the reference to a required parameter is inaccurate, as the parameter has a default value. (To be fair, relying on the default value is unlikely to work...) Part of a comment in SubversionRepo.revisions() was redundant, and could be removed. No functionality change.

97f2079e3778511944ffb6a662520580650a3993 1.0
09c016174e332eceda015d3f43d96d7e0228acf3 1.0.1
4359ddd73b009fbb356c52ea5d99cba25222ee7a 1.1
8e621dbb82d4363a85317638ad237e2817c56347 1.1.1
093ae2915b452539b44390ee4ea14987484e1eee 1.1.2