Add redmine-2.5.1 to downloads
Change default location for core_download.sh: now defaults to redmine-X.X.X-blank/ directory in the current directory, instead of redmine/ which is confusing to say the least
Be more conservative and ensure we don't break existing installs when unpacking the redmine archive
Fix rvm oopsie in core_install.sh (now works with local user rvm install)
Default to ruby 2.0.0 when creating gemset from now on
Add correct environment variables for installing rmagick on OSX
Switch core_install.sh from .rvmrc to .ruby-version/.ruby-gemset