Remove ParamsProcessor - never used it

I think we can remove a file marked as "unused" since 2010.

lib/brakeman/processors/params_processor.rb

-require 'sexp_processor'
-require 'set'
-
-#Looks for request parameters. Not used currently.
-class Brakeman::ParamsProcessor < SexpProcessor
-  attr_reader :result
-
-  def initialize
-    super()
-    self.strict = false
-    self.auto_shift_type = false
-    self.require_empty = false
-    self.default_method = :process_default
-    self.warn_on_default = false
-    @result = []
-    @matched = false
-    @mark = false
-    @watch_nodes = Set[:call, :iasgn, :lasgn, :gasgn, :cvasgn, :return, :attrasgn]
-    @params = Sexp.new(:call, nil, :params, Sexp.new(:arglist))
-  end
-
-  def process_default exp
-    if @watch_nodes.include?(exp.node_type) and not @mark
-      @mark = true
-      @matched = false
-      process_these exp[1..-1]
-      if @matched
-        @result << exp
-        @matched = false
-      end
-      @mark = false
-    else
-      process_these exp[1..-1]
-    end
-
-    exp
-  end
-
-  def process_these exp
-    exp.each do |e|
-      if sexp? e and not e.empty?
-        process e
-      end
-    end
-  end
-
-  def process_call exp
-    if @mark
-      actually_process_call exp
-    else
-      @mark = true
-      actually_process_call exp
-      if @matched
-        @result << exp
-      end
-      @mark = @matched = false
-    end
-      
-    exp
-  end 
-
-  def actually_process_call exp
-    process exp[1]
-    process exp[3]
-    if exp[1] == @params or exp == @params
-      @matched = true
-    end
-  end
-
-  #Don't really care about condition
-  def process_if exp
-    process_these exp[2..-1]
-    exp
-  end
-
-end