Partial cherry-pick: Refactor the link to interval to extract the generation of the uri and use URI to generate the urls and keep the parameters

This commit is a partial cherry-pick of b2690604. The original commit
does more than the brief description says. This commit does exactly
what the brief description says (although I should point that a change
in behavior, no matter how small, is not a refactoring).

Conflicts:

	lib/gdash/sinatra_app.rb
	views/layout.erb

The original commit was created by and on:
Author: Hector Rivas Gandara <keymon@gmail.com>
Date:   Sun Mar 10 19:21:42 2013 +0000
Support query params for details dashboard view

Some of our dashboards use query params to customize the graphs
shown. The regular and full views pass these params to the graph
descriptions, but the details view does not. This commit does two
things:
  * The query params (less 'from' and 'until') are passed to the
    dashboard.
  * The URLs generated for the graph on the regular and full views
    (which point to the detailed view for that graph) now pass on
    the query parameters (including 'from' and 'until', which are
    ignored by the details page).
Remove the Docs link in the layout navbar

The Docs link doesn't work (because the route in Sinatra is specified
with a trailing slash, which might work in other configurations, but
not in the way I use it with Rails). Plus, the Docs page is about
setting up GDash, not about using it, so it probably shouldn't be
exposed so immediately.
Use graphite_graph gem from rubygems, pessimistically at version 0.0.8

This version contains, among a few other things, a patch similar
to the code that was added to the acco fork fixing problems with
unencoded characters in Graphite URLs.

This commit virtually reverts an earlier commit (9ddd112c) which used
acco's fork but only in the Gemfile and not the gemspec. I think that we
wanted to actually use the forked gem, which never actually happened
because the gemspec was never changed. (Note that it also adds a version
constraint, which was absent before.)

However, this commit does also change the gemspec as well to add the
version constraint.
release 0.0.6