Relaxed dependencies

This should mean that people can upgrade gems more readily without
requiring a new Smashing release

smashing.gemspec

@@ -26,25 +26,25 @@ Gem::Specification.new do |s|
 
   s.files = Dir['README.md', 'javascripts/**/*', 'templates/**/*','templates/**/.[a-z]*', 'lib/**/*']
 
-  s.add_dependency('coffee-script', '~> 2.4.1')
-  s.add_dependency('execjs', '~> 2.7.0')
+  s.add_dependency('coffee-script', '~> 2.4')
+  s.add_dependency('execjs', '~> 2.7')
   if RUBY_VERSION < "2.4.0"
     s.add_dependency('sinatra', '= 2.0.4') 
   else
-    s.add_dependency('sinatra', '~> 2.0.0')
+    s.add_dependency('sinatra', '~> 2.0')
   end
-  s.add_dependency('sinatra-contrib', '~> 2.0.0')
-  s.add_dependency('thin', '~> 1.7.2')
-  s.add_dependency('rufus-scheduler', '~> 3.6.0')
-  s.add_dependency('thor', '~> 1.0.1')
+  s.add_dependency('sinatra-contrib', '~> 2.0')
+  s.add_dependency('thin', '~> 1.7')
+  s.add_dependency('rufus-scheduler', '~> 3.6')
+  s.add_dependency('thor', '~> 1.0')
   if RUBY_VERSION < "2.5.0"
-    s.add_dependency('sprockets', '~> 3.7.1')
-    s.add_dependency('sass', '~> 3.4.24')
+    s.add_dependency('sprockets', '~> 3.7')
+    s.add_dependency('sass', '~> 3.4')
   else
     s.add_dependency('sprockets', '~> 4.0')
     s.add_dependency('sassc', '~> 2.0')
   end
-  s.add_dependency('rack', '~> 2.2.2')
+  s.add_dependency('rack', '~> 2.2')
 
   s.add_development_dependency('rake', '~> 12.3.3')
   s.add_development_dependency('haml', '~> 5.0.1')