rake dependency

[jjb]

I was installing on the ubuntu/xenial32 vagrant machine which had only ruby and ruby-dev apt packages installed (in addition to the base machine) and i was getting this error below.

running gem install rake first solved the problem.

i'd submit a PR but i'm not sure where it goes in the specfile -- add_development_dependency, or another type of dependency?

ubuntu@ubuntu-xenial:/vagrant$ sudo gem install rainbow
Building native extensions.  This could take a while...
ERROR:  Error installing rainbow:
    ERROR: Failed to build gem native extension.

    current directory: /var/lib/gems/2.3.0/gems/rainbow-2.2.1/ext
/usr/bin/ruby2.3 mkrf_conf.rb

current directory: /var/lib/gems/2.3.0/gems/rainbow-2.2.1/ext
/usr/bin/ruby2.3 -rubygems /usr/share/rubygems-integration/all/gems/rake-10.5.0/bin/rake RUBYARCHDIR=/var/lib/gems/2.3.0/extensions/x86-linux/2.3.0/rainbow-2.2.1 RUBYLIBDIR=/var/lib/gems/2.3.0/extensions/x86-linux/2.3.0/rainbow-2.2.1
/usr/bin/ruby2.3: No such file or directory -- /usr/share/rubygems-integration/all/gems/rake-10.5.0/bin/rake (LoadError)

rake failed, exit code 1

Gem files will remain installed in /var/lib/gems/2.3.0/gems/rainbow-2.2.1 for inspection.
Results logged to /var/lib/gems/2.3.0/extensions/x86-linux/2.3.0/rainbow-2.2.1/gem_make.out

[mattrayner]

I second this - rake is a dependency of this gem that has not been defined. I've wasted about 2 hours tracking this down. I'd say this was a showstopper personally

[ku1ik]

This was fixed in #58 and released as rainbow v2.2.2.

[Yamakaky]

I have the same issue on debian unstable, ruby 2.3.0, rainbow 2.2.2