Added checks for old ruby. Otherwise there will be syntax errors

lib/common/common_helper.rb

@@ -124,10 +124,6 @@ def banner
   puts ' Sponsored by the RandomStorm Open Source Initiative'
   puts '_____________________________________________________'
   puts
-  if RUBY_VERSION < '1.9'
-    puts '[WARNING] Ruby < 1.9 not officially supported, please upgrade.'
-    puts
-  end
 end
 
 def colorize(text, color_code)

lib/environment.rb

@@ -17,6 +17,13 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #++
 
+require 'rubygems'
+
+if Gem::Version.create(RUBY_VERSION) < Gem::Version.create(1.9)
+  puts "Ruby >= 1.9 required to run wpscan (You have #{RUBY_VERSION})"
+  exit(1)
+end
+
 begin
   # Standard libs
   require 'rubygems'