Fix rubygems warnings and relax gem dependencies.

gush.gemspec

@@ -8,6 +8,7 @@ Gem::Specification.new do |spec|
   spec.authors       = ["Piotrek Okoński"]
   spec.email         = ["piotrek@okonski.org"]
   spec.summary       = "Fast and distributed workflow runner using only Sidekiq and Redis"
+  spec.description   = "Gush is a parallel workflow runner using only Redis as its message broker and Sidekiq for workers."
   spec.homepage      = "https://github.com/pokonski/gush"
   spec.license       = "MIT"
 
@@ -17,15 +18,15 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.add_dependency "sidekiq", "~> 4.0"
-  spec.add_dependency "yajl-ruby", "~> 1.2.1"
-  spec.add_dependency "redis", "~> 3.2.1"
-  spec.add_dependency "hiredis", "~> 0.6.0"
-  spec.add_dependency "ruby-graphviz", "~> 1.2.2"
-  spec.add_dependency "terminal-table", "~> 1.4.5"
-  spec.add_dependency "colorize", "~> 0.7.7"
-  spec.add_dependency "thor", "~> 0.19.1"
-  spec.add_dependency "launchy", "~> 2.4.3"
+  spec.add_dependency "yajl-ruby", "~> 1.2"
+  spec.add_dependency "redis", "~> 3.2"
+  spec.add_dependency "hiredis", "~> 0.6"
+  spec.add_dependency "ruby-graphviz", "~> 1.2"
+  spec.add_dependency "terminal-table", "~> 1.4"
+  spec.add_dependency "colorize", "~> 0.7"
+  spec.add_dependency "thor", "~> 0.19"
+  spec.add_dependency "launchy", "~> 2.4"
   spec.add_development_dependency "bundler", "~> 1.5"
-  spec.add_development_dependency "rake"
-  spec.add_development_dependency "rspec", '~> 3.0.0'
+  spec.add_development_dependency "rake", "~> 10.4"
+  spec.add_development_dependency "rspec", '~> 3.0'
 end