Updated README.md - Added RAILS_ENV
Updated README.md - Added RAILS_ENV

Added RAILS_ENV to gitlab:test command, so the dev database wont be wiped.

fixes https://github.com/gitlabhq/gitlabhq/issues/5756#issuecomment-29876630
8thcolor/eurucamp2014-htdsadr,8thcolor/rubyconfau2015-sadr,8thcolor/rubyconfau2015-sadr,8thcolor/rubyconfau2015-sadr,8thcolor/eurucamp2014-htdsadr,8thcolor/eurucamp2014-htdsadr