Update kaleidoscope.gemspec

kaleidoscope at /Users/dpsk/.rvm/gems/ruby-2.1.1@colorsearch/bundler/gems/kaleidoscope-39198d02ef3c did not have a valid gemspec.
This prevents bundler from installing bins or native extensions, but that may not affect its functionality.
The validation message from Rubygems was:
  duplicate dependency on rails (>= 0, development), (>= 4.0.0) use:
    add_runtime_dependency 'rails', '>= 0', '>= 4.0.0'