Use HTTPS URLs for RubyGems

[cokernel]

This modifies Gemfiles to use HTTPS URLs for RubyGems.

As a minor additional change, solrizer.gemspec now requires RSpec2, because the code

  RSpec::Core::RakeTask.new(:rspec) do |spec|
    spec.pattern = FileList['spec/**/*_spec.rb']
  end

does not function properly in RSpec3 (running rake yields the error "TypeError: no implicit conversion of Rake::FileList into String").

[jcoyne]

Looks good. @cokernel Do you have a CLA on file?

[cokernel]

@jcoyne, both I and my current institution (University of Kentucky) have CLAs on file.

[cokernel]

@jcoyne, it looks like the restriction to RSpec 2 can be avoided by replacing the Rake task above with

  RSpec::Core::RakeTask.new(:rspec) do |spec|
    spec.pattern = FileList['spec/**/*_spec.rb'].to_a
  end

This might be a little ugly, but it works in both RSpec 2 and RSpec 3.

Perhaps a simpler alternative is

  RSpec::Core::RakeTask.new(:rspec) do |spec|
    spec.pattern = 'spec/**/*_spec.rb'
  end

which also works in both versions of RSpec.