fixes #203

at least for Travis satisfaction

Add check for unsafe symbol creation

Refactor of Brakeman::Report class

 - Cleaned up some ifs
 -  Inlined some functions

 - Use locals instead of global binding
 - This opens up the possibility to clean up methods, because rendering and variables can now be seperated.

Convert simple `if` to `or` on assignment

 - Moved guard logic to check functions
 - Functions now return false if they don't hit or are skipped.

 - Broke check_argument into smaller functions
 - Removed warning code duplication
 - Added some one liners to clarify logic

CVE-2013-1854

XML parsing in JRuby

Add rel="no-referrer" to report links

with ActiveRecord::Base.send(:include,  ActiveModel::ForbiddenAttributesProtection)
should fix #288

Don't warn when calling send on user input

Use custom deep_clone for Sexp