Flask request filter

Flarf allows you to filter flask request to your specification.

Simplest example: 

    from flask import Flask
    from flask.ext.flarf import Flarf, FlarFilter

    def format_from_request(request):
        return """
               HEADER: {}\n
               header: {}\n
               PATH: {}\n
               ARGS: {}\n
               """.format(request.header.upper(),
                          request.header,
                          request.path.upper(),
                          request.args)

    flarf_filter = FlarfFilter(filter_tag='flarf_filter',
                               filter_params=[format_from_request],
                               filter_on=['includeme'])

   app = Flask(__name__)
   Flarf(app, filters=[flarf_filter])

   @app.route("/includeme")
   def index():
       return render_template("index.html")

   index.html:

   MY_REQUEST: {{ flarf_ctx('flarf_filter').format_from_request }}

Ok, so you can already do this without using Flarf in Flask and Jinja. However, 
using a filter reduced what needed to be typed out to a small degree, and is
reuseable. If you need to do the same thing over and over, you could use a 
template macro, but what if you want to something more readily done in code and
not always seen? For example, keeping a history of user requests on a per user
basis? Calculate and format variables based on other incoming variables? 

Basic examples are by nature super simple, but perhaps you can begin to see the
uses: any time you need anything specific for your views/templates you can
filter it from incoming request and have it readily available without having to
prep the info on a per-view/per-template basis.

Suggestions, input, & improvements welcomed.
