Page#text?: Updated to also check content-type for text/html

[Issue #50]

lib/arachni/page.rb

@@ -243,7 +243,9 @@ def document
     # @return   [Boolean]
     #   `true` if the page contains client-side code, `false` otherwise.
     def has_script?
-        return if !document
+        return if !document || !text? ||
+            !response.headers.content_type.to_s.start_with?( 'text/html' )
+
         return @has_javascript if !@has_javascript.nil?
 
         # First check, quick and simple.

spec/arachni/page_spec.rb

@@ -187,7 +187,7 @@ def create_page( options = {} )
     end
 
     describe '#text?' do
-        context 'when the HTTP response was text based' do
+        context 'when the HTTP response is text/html' do
             it 'returns true' do
                 res = Arachni::HTTP::Response.new(
                     url: 'http://test.com',