Update lib/svn2git/migration.rb, strips leading hyphens from tag names
Update lib/svn2git/migration.rb, strips leading hyphens from tag names

E.G.: svn/tags/--tagname becomes tagname (in stead of --tagname)
ritusingh161291/svn2git_ritu_repo,fredpalmer/svn2git,nirvdrum/svn2git,opoplawski/svn2git,aucampia/svn2git,Muktesh01/svn2git